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BOOK 83
October 11, 1996
TO ALL UNIFORMED MEMBERS
SUBJECT: BOOK 83
Each year, approximately 20,000 fires occur in the City of Los Angeles. As a result of thesefires, approximately 53 fatalities occur annually.
Determination of cause and origin is one of the most challenging and interesting duties of anyOfficer. To assist you in performing these duties, the Department is providing Book 83, FireInvestigation Manual.
The topics covered are:
• Introduction to Fire Investigation• Fire Chemistry and Behavior• Incident Indicators• Cause Determination• Conducting Investigations• Evidence• Motives• Reports and Records• Courtroom Testimony
Officers shall possess a thorough knowledge and members a working knowledge of thematerial contained in this Manual. This will ensure uniformity and effectiveness in theperformance of cause and origin determination.
WILLIAM R. BAMATTRE
WILLIAM R. BAMATTREChief Engineer and General Manager
WRB:ss: Book 83
From the office ofThe Chief Engineer…
TABLE OF CONTENTS
I. Introduction to Fire Investigation
A. Fire Department Responsibility ....................................................1
B. Incident Commander Responsibility ............................................2
C. Arson Investigation SectionResponsibility ..............................................................................3
II. Fire/Chemistry Behavior
A. Introduction ..................................................................................4
B. Fire/Chemistry Terms ...............................................................4-6
C. Chemistry of Fire ....................................................................6-11
D. Building Construction ...........................................................11-26
III. Incident Indicators
A. Introduction ................................................................................27
B. Structures .............................................................................27-38
C. Vehicles ................................................................................38-43
D. Wildland ...............................................................................43-58
E. Explosions ............................................................................58-63
IV. Cause Determination
A. Elements of a Fire Cause......................................................64-66
B. Accidental Fire Causes
1. Electrical Fires ...........................................................67-892. Cigarette-caused Fires ..............................................89-933. Other Accidental Fires ............................................93-107
C. Incendiary Fire Causes .....................................................107-112
V. Conducting the Investigation ....................................................113-122
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VI. Evidence
A. Types of Evidence ...................................................................123
1. Direct Evidence .....................................................123-1242. Circumstantial Evidence ..............................................1243. Evidence Handling ................................................124-1264. Chain of Evidence.........................................................126
VII. Motives
A. Motive Types ....................................................................127-131
VIII. Reports and Records
A. Introduction ..............................................................................132
B. Definitions of Fire Causes .......................................................133
C. Fire Loss Estimation .........................................................133-137
D. Fire Report Requests .......................................................137-138
E. Subpoena Service ............................................................138-139
F. 902 Operation ..................................................................140-143
G. Fire Incident Report Requests..................................................143
IX. Courtroom Testimony
A. Subpoenas .......................................................................144-145
B. Preparing for Court ...........................................................145-146
C. Testifying ..........................................................................146-147
D. Testifying as an Expert Witness .......................................147-149
E. Definitions ........................................................................149-150
X. Arson Laws
A. California State Penal Code .............................................151-156
B. California State Insurance Code ..............................................156
C. Los Angeles Municipal Code ...................................................157
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XI. Glossary ...................................................................................................158-168
XII. Bibliography ............................................................................................169-170
XIII. Arson Bulletins ........................................................................................171
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I. INTRODUCTION TO FIRE INVESTIGATION
A. THE FIRE DEPARTMENT'S RESPONSIBILITY
The Fire Department, under the City Charter, has the authority to investigatefires occurring within the City of Las Angeles.
The responsibility for the investigation of fires is shared between the Bureau ofFire Suppression, which has the primary responsibility for the causedetermination of fires, and the Bureau of Fire Prevention.
In arson fires, this responsibility is translated into the protection of the publicfrom those people who set fires. Under a written Letter of Agreement with theLos Angeles Police Department, the Fire Department, with the exception ofassociated major crimes such as a homicide, is responsible for the prevention,enforcement and prosecution of the crime of arson within the City of LosAngeles.
In non-criminal fires, this follow-up responsibility translates into a moral andethical obligation of the Fire Department, as the first responder who possessesthe most immediate facts and evidence as to the cause and circumstances ofthe fire, to make an adequate investigation. In recent years, the most probablecause of a fire and the facts of the investigation as determined by the FireDepartment have been increasingly used as a basis for subrogation in small andlarge loss fires, and fires resulting in injury and death.
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B. THE INCIDENT COMMANDER'S RESPONSIBILITY
The Bureau of Fire Suppression and Rescue has the primary responsibility todetermine the cause of all fires, criminal and non-criminal. They will completethe preliminary investigation on all incidents. In doing so, they may request theArson Investigation Section for assistance or an Arson Unit may automaticallybe dispatched by OCD.
The Bureau of Fire Suppression and Rescue also has the follow-upinvestigation responsibility of fires where the total loss is less than $25,000.
This Fire Investigation Manual is designed to assist you, the IncidentCommander, in:
Determining Fire Cause and the Point of Origin
Incident Indicators
How to Conduct the Investigation
Identification and Preservation of Evidence
Motives of the Firesetter
Documentation Needed for Reports and Records
Preparation for Testifying as an Expert Witness
Arson Laws
Terminology Used in the Fire Service
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C. THE ARSON INVESTIGATION SECTION'S RESPONSIBILITY
As per the Manual of Operation, the responsibility for determining the mostprobable cause of a fire rests with the Incident Commander. Theseinvestigations are to determine the cause of the fire. The purpose of fire causedetermination is to establish how the fire started and the motive for starting it.
For the purpose of assigning investigation responsibility, the term investigationas applied to a fire will be divided into a preliminary and follow-up investigation.The preliminary investigation will refer to the fire scene investigation andsubsequent investigation needed to establish the cause.
The follow-up investigation, of an arson fire, refers to the criminal investigationnecessary to seek the prosecution of an arsonist. In an accidental fire, thenon-criminal investigation necessary to determine the contributing factors,liability, fire code violations and needed fire code revisions.
The Arson Investigation Section is organized to provide limited fire investigationservice for the City of Los Angeles on a 24-hour basis.
The Arson Section is responsible for the investigation of fires in which there isknowledge or suspicion the crime of arson has been committed or attempted.The responsibility also extends to the detection and apprehension of those whoare involved in criminal fires.
The Arson Section is required to complete a narrative report on all firesinvestigated and to maintain these records as a source of documentation foruse in criminal and civil cases.
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II. FIRE CHEMISTRY/BEHAVIOR
A. INTRODUCTION
Members that are responsible for or the investigation of fire scenes must have aworking knowledge of the behavior of fire since:
The member is often required to interpret the aftermath of a fire.The member is frequently required to use both technical and/or generalexplanations of fire behavior in legal proceedings.
A knowledgeable understanding of the behavior of fire helps to demonstrate themember's expertise in the area of fire cause determination.
A member's understanding and ability to explain the behavior of fire will addcredibility to court testimony and to the member's opinion.
A basic understanding of the behavior of fire is the foundation from which anyfire cause investigation will be developed.
One of the more popular tactics of arson defense attorneys is to attack themember's credibility with regard to fire behavior, therefore, a good basicunderstanding of the subject adds to the credibility of the member as an expertwitness.
B. FIRE CHEMISTRY
1. Terms relating to Fire Chemistry
British Thermal Unit (B.T.U.)
The amount of heat required to raise the temperature of one pound ofwater one degree Fahrenheit (measured at 60 degrees F.).
Combustible liquids
Liquids having a flash point at or above 100 degrees F.
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Fire
Rapid oxidation of a substance accompanied by the release of energyusually in the form of heat and light.
Fire point
The lowest temperature of a liquid in an open container at which vaporsevolve fast enough to support continuous combustion.
Flammable limits
The term "lower flammable limits" (LFL) describes the minimumconcentration of vapor-to-air below which propagation will not occur inthe presence of an ignition source. The "upper flammable limit" (UFL) isthe maximum vapor-to-air concentration above which propagation offlame will not occur.
Flammable liquids
Liquids having a flash point below 100 degrees F.
Flash Point
The minimum temperature at which a liquid gives off vapors in sufficientconcentrations to form an ignitable mixture with air near the surface ofthe liquid.
Heat
A form, of energy associated with the motion of atoms and molecules.
Heat of combustion
The amount of heat released during the complete oxidation of asubstance.
Ignition temperature
The minimum temperature to which a substance must be heated in air inorder to initiate or cause combustion, independent of the heatingelement or source. The ignition temperature of ordinary combustibles isbetween 300 and 1000 degrees F.
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Oxidation
As a substance burns, it mixes with oxygen and produces heat.
Specific gravity
The ratio of the weight of a solid or liquid substance to the weight of anequal volume of water.
Temperature
The quantity of heat concentration. The intensity of heat is measured indegrees (Fahrenheit or Celsius).
Vapor density
The weight per unit volume of a pure gas or vapor. In fire protection,vapor density is reported in terms of the ratio of the relative weight of avolume of vapor to the weight of an equal volume of air under the sameconditions of temperature and pressure.
A vapor density less than 1.0 indicates a vapor lighter than air.
A vapor density more than 1.0 indicates a vapor heavier than air.
C. CHEMISTRY OF FIRE
1. Classification of fires
Class "A” fires are fires involving ordinary combustible fuels.
Class "B" fires are fires involving liquid fuels.
Class "C" fires are fires involving energized electrical equipment.
Class “D" fires are fires involving combustible metals.
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2. The fire triangle
Heat
Fuel
Oxygen
3. The fire tetrahedron
In reality, fire has four parts which are necessary for self-sustaining,open flaming combustion:
Heat
Fuel
Oxygen
Uninhibited chain reaction among all parts of the tetrahedron.
In the flame, many chemical reactions occur which produce additionalheat. When certain extinguishing agents are introduced, it breaks up thischemical reaction and extinguishes the fire without affecting the heat,fuel, or oxygen sides of the fire triangle. These extinguishing agents are:
Dry chemical
Halon
4. Pyrolysis
Pyrolysis is the chemical decomposition of matter through the action ofheat. Early indications of the pyrolysis process are usually observed asdiscoloration of the fuel. As pyrolysis continues, combustible gases arereleased and a black carbon residue called "char" remains. The fuelcontinues to dry and char as the fuel continues to absorb heat. Aspyrolysis continues, sufficient combustible gas is evolved to produce anatmosphere rich enough to support combustion.
If the fuel continues to be heated slowly, but there is not sufficient heatpresent to reach ignition temperature, pyrophoric carbon may result.
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Normally, minimum- temperature associated with development ofpyrophoric carbon may become hot enough to cause surrounding fuelsto reach ignition temperature. At the point of origin, combustiblematerials may be totally carbonized while adjacent areas may beundamaged.
5. Ignition and Combustion of Wood Products
As fuel is first heated to a point where its surface reaches the* boilingpoint of water, flammable vapors are released.
As heating continues/increases, the drying process continues andignition of the flammable vapors occurs when the temperature issufficient to cause these vapors to ignite.
6. Heat Transfer
The transfer of heat is usually the key element in ignition (andextinguishment) of most fires. Heat is transferred in four ways.
a. Conduction
The transfer of heat from one object to another through directphysical contact.
Examples: Metal pipes in the fire area conducting heat andspreading the fire through walls or othercombustible assemblies to involved areas.
Heated steel structural members spreading the fireto uninvolved areas.
b. Convection
The transfer of heat by some circulating medium (liquid or gas).This is the form of heat transfer most responsible for fire spreadin structural fires.
Example: The spreading of fire from lower to upper structuralareas when upper areas become heated to theirignition temperature.
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c. Radiation
The transfer of heat as energy traveling through space ormaterials as waves.
Example:Exposure problems in large fires.
d. Direct flame impingement
Direct flame contact with combustibles.
7. Phases of fire
Most fires (and especially those in structures) can be divided into threeseparate phases:
a. Incipient phase (Growth)
Although actual flame temperatures can reach 1000 degrees F.,temperatures in the surrounding area are not greatly increased.There is free burning with open flame. Oxygen in the arearemains near 21%. Thermal updraft causes heat to accumulate atthe higher portions of the area.
b. Free burning phase (Fully developed)
Air from the surrounding atmosphere is drawn into the fire."Mushrooming" may take place and flame is present. oxygencontent of area is usually reduced to 16% - 18%. Fire gaseswhich may be present are carbon, carbon monoxide, carbondioxide, water, sulfur dioxide, etc., depending on fuel, heat, andgeneral environment. "Flashover" frequently occurs during thisphase.
c. Smoldering phase (Decay)
Free burning may cease in the fire area. Area fills with densesmoke. Oxygen may drop below 15%. Temperatures may reach1000 degrees F. throughout the area. Improper/uncontrolled airadmission may result in "backdraft".
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8. Backdraft
A backdraft is defined as an explosion or rapid burning of heated firegases resulting from the introduction of oxygen when air is admitted intoa building heavily charged by smoke from a fire which has depleted theoxygen content of a building.
Cause of backdrafts:
Carbon monoxide is one of the most common gases found in structuralfires and is highly flammable.(Explosive limits = 12.5% - 74%).
Carbon monoxide usually collects at the upper areas of a fire-involvedstructure and the introduction of air from below may produce thenecessary air-to-vapor mixture to bring the carbon monoxide into itsflammable limits.
The ignition temperature of carbon monoxide (1128 degrees F.) is wellbelow the temperature found at the upper areas of a structure involvedin fire.
Flammable gas + explosive (flammable) range + ignition source =explosion.
Backdrafts (explosions) often produce injuries to fire personnel.Questioning fire personnel may help identify a backdraft:
Heavy smoke conditions on arrival.
Lack of visible flame.
Improper method of entering a structure may cause a backdraft.
Movement of smoke prior to explosion.
Structure may appear to breathe.
Whistle, jet or train sound
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9. Flashover
Flashover is the stage of the fire when all combustibles in an area havebecome heated to their ignition temperature, then ignite simultaneously.
Flashover occurs when heat produced by-'the fire collects at ceiling leveland is returned to lower areas by thermal radiation feedback.Combustible materials are heated to their ignition temperatures and fireflashes over-large areas (may involve all combustibles in the area).Flashover may cause an area to appear to have been exposed toflammable accelerants. Careful examination, however, should indicate:
Burning over top surfaces of materials.
Lack of normal fire spread from point of origin.
Lack of accelerant residue.
D. BUILDING CONSTRUCTION
1. Types of Buildings (Title 24)
Type I - Fire Resistive
The structural elements in Type I Fire-resistive buildings shall be of steel,iron, concrete, or masonry. Walls and permanent partitions shall be ofnoncombustible fire-resistive construction except that permanentnon-bearing partitions may have fire-retardant treated wood.
Type II - Noncombustible/fire-resistive, one-hour, or no-hourconstruction.
Construction in which walls, partitions, and structural members are ofnoncombustible material but do not qualify as Type I Fire-resistive.
Type III - Ordinary construction
Construction in which exterior bearing walls or bearing partitions ofexterior walls are of noncombustible materials and have a minimumhourly fire-resistive rating. Wood allowed for interior use.
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Type IV - Heavy timber construction
Construction where exterior bearing and non-bearing walls arenoncombustible and have a minimum fire-resistive rating of four hours.Columns, beams and girders are commonly heavy timber with woodfloors and roof construction built without concealed spaces. "
Type V - Wood frame construction
Construction in which exterior walls, bearing walls, partitions, floors androofs as well as their supports are wholly or partly wood or othercombustibles.
2. Structural Loads and Loading
Dead loads
The weight of the building and any equipment permanentlyattached or built-in.
Live loads
Any load other than a dead load. Live loads vary with intended oractual use of the structure. Examples of common live loads areoccupants, storage, and furnishings. Fire operations increase thelive loads both in water accumulation and fire personnel.
Impact loads
Loads which are delivered in a short period of time. Impact loadsmay be more harmful when supported as dead or live loads.Examples of common impact loads are explosions, wind (lateralanalysis), and earthquakes.
Fire loads
The total number of British Thermal Units (BTU) which might beevolved during a fire in the building or area under considerationand the rate at which the heat will be evolved. Occupancy typehas a direct relationship to fire load and generally dictates thepossible fire load.
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3. Building elements and considerations for the fire scene investigation.
Walls and Partitions
Rating of fire walls.
Wall finish and certifications.
Wall integrity.
Ceiling assemblies
Concealed spaces acting as flues.
Ceiling integrity.
Floor assemblies
Floor coverings.
Floor integrity.
Concealed spaces acting as flues.
Attic and roof assemblies
Usually susceptible to fire spread.
Often constructed of unprotected materials.
Storage of combustibles.
Attic areas (Unprotected concealed space) cannot exceed 3000square feet without fire walls.
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4. Roof Construction
Gable Roof
Conventional or ordinary construction consists of a ridge board andrafters from the ridge board down to and across the outside walls (studs). Ridge and rafters are usually 2 by 6 inches Or larger. Rafters areusually 16 inches to 24 inches "on center". Additional support is providedby collar beams and ceiling joists. Roofs are constructed in semi-flat tosteep pitches.
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RIDGE BOARD
RAFTER
CEILINGLING JOIST
TOP PLATES
STUD
GABLE ROOF
Hip roof
Similar to gable roof. Ends of roof terminate in "hip". conventional orordinary construction consists of ridge pole and hip rafters from the ridgeboard down to and across the corners at the outside walls. Valley raftersare utilized where two roof lines are joined together. Ridge and raftersare usually 2 by 6 inches or larger. Rafters are usually 16 to 24 inches"on center". Various degrees of pitch are utilized.
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RIDGE BOARD
HIP RAFTER
PLATEJACK RAFTER
VALLEY RAFTER
COMMON RAFTER
Flat roof
Wood joists (rafters) of various sizes laid across the outside walls oroutside walls to interior walls or structural supports. Joists may also besuspended by metal hangers. Joists are covered with 1 by 6 inchsheathing or plywood and composition roofing material.
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ROOFING MATERIAL
4' X 8'PLYWOOD OR1" X 6" SHEATHING
WOODEN JOIST
FLAT ROOF
Bridge truss roof
Wooden truss members constructed from 2 by 12 inch lumber withsloping ends. Usually a heavy grade of construction. Metal tie rods maybe used vertically for additional support. Joists are 2 by 6 inches and 2by 8 inches covered with 1 by 6 inch sheathing and composition roofingmaterial.
BRIDGE TRUSS ROOF
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ROOFING MATERIAL
WOOD SHEATHING
RAFTERS
TOP CHORDCOMPRESSION
BOTTOM CHORDTENSION
METAL SUPPORT RODS
Arched roofs
Bowstring arch roof
Arch roof with tie rods and turnbuckles offering lateral support. Tie rodswith turnbuckles are used-below each arch member to support theexterior walls. Tie rods may pass through exterior walls to an outsideplate facilitating identification. Tension is maintained by the turnbuckles.Top chords of arch members may utilize laminated 2 by 12's or larger.Two by 10 inch rafters are covered by 1 by 6 inch sheathing andcomposition roofing material.
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RAFTERS
ROOFING MATERIAL
WOOD SHEATHINGOPTIONAL
TOP CHORDCOMPRESSION
STEEL RODBOTTOM CHORDTENSION
TURNBUCKLE
BOWSTRING ARCH
Ribbed (trussed) arch roof
Usually large size (2 by 12, 2 by 14 inch) wooden members utilized toconstruct truss arch. Some arches have multiple laminated beams toform one arch. Rafters (2 by 10 inch or larger) are covered with 1 by 6inch: sheathing and composition roofing material.
RIBBED ARCH ROOF
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RAFTERS
WOOD SHEATHING
ROOFING MATERIAL
TOP CHORDCOMPRESSION
DETAILBOTTOM CHORD
TENSION
Sawtooth roof
Constructed in commercial buildings to yield additional light andventilation. Constructed with rafters of 2 by 8 inches or larger, andutilizes wood and/or metal supports for bracing to provide additionalstrength. Vertical portion is usually "wired" glass with openable panes.Sloping portion is covered with 1 by 6 inch sheathing or plywood andcomposition roofing material.
SAWTOOTH
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ROOFING MATERIAL
WOOD SHEATHINGGLASS
RAFTER
Panelized roof
This roof may be found on structures constructed of woody masonry, orconcrete tilt-up slabs. This roof consists of four major components.
Laminated beams
Purlins
2 by 4 inch joists
½ or 5/8 inch plywood decking.
4’ X 8’PLYWOOD
JOIST
12’ TO 40’
BEAM
METAL HANGER
DETAIL
PURLIN
ROOFING MATERIAL
PANELIZED ROOF
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Metal Gusset Plate Construction
Drawing "All (Residential)
Rough carpentry wood trusses used both in residential (Drawing "All)and commercial (Drawing "B") applications utilize 2 X 4's held togetherby metal gusset plate connectors. Trusses are constructed of top chords,bottom chords, and webbing (supports between the top and bottomchords). The trusses are held together by metal gusset plate connectors.Trusses are supported at their outside edge only unless used as acantilever truss. Eighteen gauge roof truss clips are nailed to the bottomchords and to the top plate of the interior wall. Common on-centerspacing is 2 feet and may be covered with 1/2 inch plywood.
ROOFING MATERIAL
TOP CHORDCOMPRESSION
PLYWOOD
METAL GUSSET PLATE
WEBBING
BOTTOM CHORDTENSION
METAL GUSSET PLATE CONSTRUCTION
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Metal Gusset Plate Construction
Drawing "B" (Commercial)
METAL GUSSET PLATE CONSTRUCTION
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WEBBING
TOP CHORDCOMPRESION
PLYWOOD
BOTTOM CHORDTENSION
METAL GUSSET PLATE
Open Web Construction
Open web construction consists of bottom and top parallel woodensupporting beams (chords) which are cross connected by steel tube webmembers. The steel, tube web members are prefabricated from 1 to2-inch cold rolled steel tubing with the ends pressed flat into asemicircular shape and a hole punched through each end. Theseflattened ends are then inserted into slots in the chords. Steel pins (up to1 inch) are driven through the chord members and through the flattenedends of the web members completing the assembly.
OPEN WEB CONSTRUCTION
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PLYWOOD
ROOFINGMATERIAL
TOP CHORDCOMPRESSION
METAL OPEN WEBBING
BOTTOM CHORDTENSION
UNSUPPORTED
Wooden "I" Beam Construction
Wooden "I" beam construction consists of three main components: topchord, bottom chord and a 3/8 inch plywood stem. The stem is joined tothe top and bottom chords by a glued edge joint. 2 X 4 Is are used aschords. Some chords resemble plywood because of laminations. Thelaminations run horizontally in the chords. Common on-center spacingfor this construction is 2 feet. Half -inch plywood is utilized for thedecking.
WOODEN “I” BEAM
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TOP CHORD COMPRESSPLYWOOD
ROOFINGMATERIAL
BOTTOM CHORDTENSION
PLYWOOD
END VIEW
5. Building construction Illustration
The following illustration is an example of constructionterminology and techniques that are useful in developing a basicknowledge of construction fundamentals-.
WALL FRAMEWORK
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1. TOP PLATE2. KICKER BLOCK3. HEADER4. STUD5. TRIMMER6. FIRE BLOCKING7. DIAGONAL BRACING8. SILL HERDER9. TRIMMER10. SUDFLOORING11. SOLE PLATE12. FLOOR JOIST13. SOLID BLOCKING14. CRIPPLE STUDS15. TREATED PLATE
III. INCIDENT INDICATORS
A. INTRODUCTION
In most cases, damage from fire leaves behind distinctive patterns. The type ofmaterial burning, the manner in which it was ignited and how long it burnsdictates the pattern(s) that remain. The burn patterns may be very obvious orextremely subtle, requiring an exhaustive search. The fire scene Investigatormust be able to follow the path of the fire by reading these patterns.
The area of origin can best be determined by having the knowledge andexperience to recognize these patterns or incident indicators. Burn patterns andthe ability to recognize them are fundamental to the fire scene investigator.
There are definite relationships between the point of origin and the fire cause.Conclusions should be based on the preponderance of the indicators and thetotal fire scene.
B. STRUCTURES
1. Preliminary observations
The process of determining cause and origin of a fire starts prior toarrival on the fire scene. Some considerations are as follows:
Type of occupancy
Timeof day and day of week
Color of fire and smoke
Complete combustion often produces little or no smoke. Dense,heavy smoke often indicates incomplete combustion as the lackof sufficient oxygen usually causes flames to be darker. The colorof flames may indicate the types of materials being burned. Asthe amount of hydrocarbons increase, the flames will becomedarker and more orange in color.
The process continues through the extinguishment phase.
How well developed was the fire upon arrival?How fast was the fire developing?How difficult was the fire to extinguish?How did firefighting tactics and strategy affect the fire travel?
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2. Scene investigation
Accurate cause and origin determination requires the fire sceneinvestigator to develop a well organized and coordinated procedure.First, examine the entire exterior of the structure. Then examine theinterior of the structure, working from. the LEAST to the MOST damagedfire areas. It is imperative that ALL areas be examined, to insure thatnothing of significance is overlooked.
ONE INDICATOR IS NOT SUFFICIENT. TAKE ALL AVAILABLEINDICATORS INTO CONSIDERATION. CLEAR YOUR MIND AND TAKEA SECOND LOOK. MENTALLY, MOVE THE POINT OF ORIGIN TODIFFERENT PLACES AND TRY TO DISPROVE YOUR OWN THEORY.
3. Burn patterns
Burn patterns are the burned areas as opposed to unburned areas andtheir relationship to each other. This will be indicated by the angle, orwhere the burn IS as opposed to where it is NOT. Convection andradiation play a major role in producing burn patterns.
Factors that may influence the burn patterns:
Fuel load
Venting
Firefighting activities
Weather
Complete and systematic removal of debris may be necessary to obtaina clear, unobstructed view of patterns.
a. General
The fire scene investigator should work backwards in relation tothe fire's travel or spread.
Examine the areas of least damage and work toward areas ofmost severe damage.
Entire structure must be examined and conditions recorded.
Ceiling damage may help locate the point of origin.
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The area above the point of origin is usually exposed to heat andflame for longer periods and may result in holes in the ceiling.
The normal growth of a fire is usually upward and outward. Thisburning usually produces a “V" pattern.
“V" patterns may help to identify point of origin and are usuallyfound on walls, therefore, once ceiling damage has beenidentified, walls should be evaluated next, then patterns at floorlevel.
“V" patterns will usually point toward the origin of the fire.
Shape/characteristic of “V" pattern:
Wide “V" pattern with diffused line of demarcation usuallyindicates a slow smoldering combustion.
Narrow “V" pattern with sharp line of demarcation mayindicate flaming, rapid combustion.
Inverted “V" pattern with sharp line of demarcation mayindicate flaming, very rapid combustion; possiblepresence of flammable accelerants.
“V" may only be identifiable from a distance in larger structurefires.
In some cases, “V" may be vertical, horizontal or a combination ofboth.
“V" patterns may extend around corners, walls and doors.
Interior structural elements may form “V" patterns.
b. Char patterns
The chemical composition of wood and modified wood consistsprimarily of carbon with other elements such as hydrogen andoxygen with lesser amounts of nitrogen.
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Douglas fir burns at the rate of approximately one inch in 40-45 minutes.
Hardwoods burn at the rate of about 3/4 inch in 40-45 minutes and pineburns at a faster rate than fir.
CHAR DEPTH MEASUREMENTS SHOULD BE USED AS ANINDICATOR ONLY!
NORMAL WOOD
CHARDEPTH
CHAR BASE
CHAR LAYERPYROLYSIS
ZONE
PYROLYSISZONEBASE
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If a cross section of the wood is cut and the line of demarcationexamined, it will show a sharp line of charring between the burned andunburned areas for high temperatures. However, if the area between theburned and unburned is overlapping showing a grey or brown area, thenthis is a good indication of a slow fire with lower temperatures.
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DEPTH OF CHAR
WOOD
MEASURING TOOL
CHAR
A fast fire does not give heat time to penetrate the wood. A slow firewould give the heat time to penetrate and there would be a "gradual"decline from unburned to charred wood. Wall coverings must be takeninto consideration in regards to flame spread. How long would thesecoverings protect the wood?
When exposed to high temperatures, such as those associated withflammable liquids, wood will usually develop deep, shiny, rolling,alligatoring blisters.
Relative depth of char usually indicates length of time materials havebeen exposed to the flame. Deep char is usually found near the point oforigin and may be a good indicator to help locate the point of origin.
LENGTHWISECUTS
INDICATIVE OF FAST BURN:SHARP LINE OF DEMARCATIONBETWEEN BURNED ANDUNBURNED AREAS
INDICATIVE OF SLOW BURN:GRADUAL DECREASE FROMCHARRED TO UNBURNED WOOD
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The char patterns will vary based upon the fuel load. Otherfactors that may effect charring are:
Ventilation
Age of the product
Moisture content
Hardness/density of the product
Temperature of the fire
Existing fuel load around the product
Firefighting tactics & strategy
Expect deeper char around doors, windows and other openings.This will usually be caused by the flames venting out theseopenings as the fire seeks additional oxygen.
c. Low burns
Fire penetrates floor
Consider fuel load.
Consider venting.
Consider floor covering.
Consider radiant heat patterns.
Consider sharp lines of demarcation which may indicatethe presence of flammable liquids.
Fuel load
Table/chair legs
Undersides of tables/chairs
Door bottoms
d. Lowest level of burning
Burning in a downward direction is usually very slow. The point oforigin is usually located at or near the lowest level of burning.
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Remove debris in layers when searching for lowest level ofburning.
Determine if debris is normal for given occupancy or area.
Establish times when various fuels/materials were heated/burnedand fell to floor.
Examine undersides of contents for fire damage.
Fire damage to the underside of contents may indicate point oforigin at lower level (chairs, sofas, tables, etc.).
Examine undersides of structural elements for fire damage(shelves, doors, window sills etc.).
e. Spalling
Spall is the explosive breaking off of pieces of masonry materialssuch as concrete or brick during exposure to fire. Great care mustbe used while evaluating the significance of concrete spalling.Spall only suggests a possibility of the presence of flammableliquid, and in and of itself, does not prove the presence of aflammable liquid.
Spalling can be caused by rapid contraction of the surface of theconcrete as a result of application of hose streams. It may alsobe caused by expanding moisture pre-existing in the concreteprior to the fire.
f. Ghost marks
Asphalt tile is usually applied by use of a mastic adhesive. Mostflammable liquids are petroleum-base and will be a solvent to themastic. As the flammable liquid soaks into the joints of the tiles, itwill mix with and liquefy the mastic. The tightness of the jointsregulates the amount of liquid seeping under the tile.
In most cases, ghost marks are caused by the application of aflammable liquid to a surface covered with asphalt tile. Ghostmarks will leave a dark, discolored mark where the tile edge waslocated.
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g. Smoke residue color-and density
Black, sooty smoke usually indicates a hydrocarbon product(flammable liquid or foam).
Dark, gray smoke adheres to surfaces and is usually sticky anddifficult to wipe off. It is usually indicative of a slow or smolderingfire.
The farther away from the origin, the higher the smoke line. Thiswill-vary with the fuel load.
h. Light bulbs
When subjected to 900 degrees F., may swell toward the point ofheat.
Under fire conditions, the gas pressure in the light bulb increaseswhile the glass is softened on the side which is heated most bythe fire.
i. Light fixtures
Improperly installed light fixtures may cause fires in nearbycombustible construction materials (joists, studs, insulation, etc.).
The fire may be slow starting and may be characteristic of lowtemperature ignition. There may be deep charring or pyrophoriccarbon in the area of origin.
In fluorescent fixtures, the ballast transformer can often causefires when the pitchblende inside the transformer breaks down.The transformers are designed to operate continuously atapproximately 90 degrees F, but the temperature often goeshigher. This heat can melt and vaporize the pitchblendesometimes igniting combustible ceiling material.
Ballast transformers have a life expectancy of 15 years. Manyolder ones still in use are beginning to break down.
Check for the odor of the burned ballast.
Check for leakage of ballast filler material.
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j. Glass as an indicator.
Factors that effect glass behavior
Age
Thickness
Type
Temperature variation (inside to outside)
Country of manufacture
Glass objects located throughout the structure can be affected bysmoke, heat and flame, and therefore assist with point of originidentification. The effects of these products vary with:
Heat buildup
Intensity of fire
Speed of fire spread
Distance from the fire
Smoke stain and glass
Smoke production varies with the type of material burned,rate of burning, and duration of burning. Smoke stainsmust be used as an indicator only due to the manyvariables affecting its presence.
Accumulates on cool/cold surface.
Stops forming when temperatures reach 700 degrees F.
Baked on smoke stain (soot) will burn off when exposedto direct flame.
Crazing of glass as an indicator.
Crazingis usually caused by rapid buildup of heatduring the fire.
Extent and size of crazing varies with the thicknessof glass, relative exposure to fire, and type ofglass.
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Heat fracturing of glass
Usually larger than crazed glass.
Usually caused by slower heat buildup.
Checkering of glass (half-moon shape found on surface of glass).
Usually results from water being applied to heated glass.
Usually indicates glass was in its frame when fire streamswere used.
Broken glass due to mechanical force
Requires careful examination.
Check the glass for concentric fractures and radialfractures.
Can indicate forced entry prior to fire.
May produce protected areas under the glass.
Explosion will cause shards of glass to be found atvarious distances outside of structure.
Location of glass within debris
Level that glass is located in debris.
Determine what time during the fire the glass became partof the debris.
k. Annealing of springs
The term annealing, when applied to spring steel, means to makeless brittle. This condition is the result of the steel beingsubjected to heat and allowed to slowly cool.
Annealing can occur to any type of spring, whether in a vehicle orin furniture.
The annealing temperature is dependent on the type and mass ofthe steel.
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l. Melting points of metal
Melting of metal within the structure may indicate an intense fire.
Possible indicator of extreme heat at or near floor level.
Extreme heat may be the result of the use of flammable liquids.
The melting of different materials in the structure can be anindicator of the type of temperatures reached during the fire.
m. Calcination of drywall/sheetrock
Naturally contains 21% water which is chemically bound in theproduct.
Dehydration of gypsum is called "calcination".
Heat exposure causes it to undergo calcination (105+degrees F.).
The calcination process causes distinct lines to appear.This can be observed by looking at the edge of the board(cross section).
C. Vehicles
The average automobile contains over 300 pounds (approximately 13%) ofplastics which are derived from petroleum products. Vehicles also contain othermaterials, such as gasoline, diesel fuel, motor oil, transmission and brake fluids,and battery acids, which among other things, are subject to combustion. Inaddition to these components, a normal vehicle contains mechanical systemswhich generate electrical sparks and heat during its normal operation. Thesesources of ignition are capable of starting a fire under the proper conditions.Engineering and safety designs by the manufacturer play an important role inprotecting these vehicles from accidental fires. Accordingly, accidental firesinvolving vehicles are not as frequent as commonly believed.
1. Fire scene investigation
a. Fires involving vehicles require both a fire scene examination anda detailed vehicle examination.
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b. As in other fires, vehicles should be worked from the area of leastdamage to the area of most damage in an attempt to locate thepoint of origin.
c. Begin your investigation PRIOR to overhaul.
d. Survey of the surrounding area may help in the overall fire sceneexamination. The following indicators may be of importance:
Gas cap missing.
Accelerant residue under or near vehicle which may be takenfrom the soil.
Fire damage to the surrounding area should be noted.
An accelerant container may be found in the immediate area.
A remote area may indicate vehicle was possibly stolen andtaken to that location to be burned.
e. Exterior vehicle examination may be helpful in the fire causedetermination. This should include an examination of thefollowing:
Fire damage relating to roof, tires, wheels and other bodycomponents.
Make note of collision damage.
Check for multiple fires, although strict attention must be given toprove that one fire did not communicate to the other.
Burn patterns may be evident on the vehicle especially when aflammable liquid was used to accelerate the fire.
Check for obvious missing parts such as tires, wheels, doors,etc., which may possibly indicate a motive for the fire.
Check for flammable liquid residue around the moldings offenders, doors, hood, trunk and windows.
Check trunk for the usual contents (spare tire, jack, etc.). Anempty trunk should be considered suspicious on older modelvehicles.
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f. Examination of the vehicle's interior may reveal indicators as tothe cause of the fire to include the following:
A fire that is intentionally accelerated with flammable liquid in thepassenger compartment will have a total, even burn from front torear. The roof line will be severely distorted if allowed to burn forten to fifteen minutes. Generally, the seats will show evidence ofannealing (weakening and collapsing).
Flammable liquid containers may be left in the vehicle by thesuspect thinking they will be consumed in the fire.
Regardless of the container used (metal, glass or plastic), someportion will be left as evidence.
Flammable liquid residue may be present in floor carpets, undermats, in seat cushions or along door panels.
Check for annealing of springs in seat cushions which is anindicator of extreme heat, but in and of itself is not necessarily anindicator of an incendiary fire.
Examine the windows of the vehicle, noting their position and ifthey had been broken out prior to the fire (lack of heat/smokedamage).
Examine doors to establish if forcible entry had been made priorto the fire.
Examine interior of vehicle to establish if accessories may havebeen removed/stolen prior to fire.
Check to see if ignition key is in its proper place or if the vehiclemay have been "hot-wired".
Make a complete search of the vehicle for evidence of incendiarydevices.
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g. Examination of vehicle's fuel system should include the following:
Inspect the integrity of the fuel tank and its components.
Examine the tank fill cap and spout.
Examine fuel lines and connections (check for tool marks ortampering).
Vehicles equipped with catalytic converters present specialfire-related problems. A properly operating catalytic converter canreach internal temperatures of 1600 degrees.
An improperly operating converter may generate an externaltemperature of approximately 2500 degrees Fahrenheit. Thisheat can be conducted through the bottom of the vehicle causingcombustible material in the interior to ignite.
Fires in grass and brush have been caused by vehicles parkedoff the road where the heat from a catalytic converter has beenthe source of ignition.
h. Examination of the engine compartment area may revealevidence as to the cause of the fire.
Electrical engineers have greatly reduced the possibility of a firefrom a short circuit in a "factory" (non-modified) vehicle."After-market" additions to the electrical system (stereocomponents, etc.), however, do cause fire related problems.
(1) Fuses
Fuses are replaceable conductors with a low meltingpoint. If the current passing through the fuse exceeds itscapacity, the conducting material will melt and stop theflow of electricity.
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(2) Circuit breakers
Circuit Breakers are generally used to protect electricmotors that are used intermittently. They are normallyfound on auxiliary items such as power windows andtailgate windows.
(3) Fusible links
Fusible links are a section of wire approximately fourgauges smaller than the regular wire being used. If anoverload occurs, the link will burn out before the regularwire is damaged.
(4) Battery
Although uncommon, batteries have been known toexplode, thereby being a source of ignition. This can becaused by an excessive charging rate that causeshydrogen gas to be released. If there is inadequateventilation, a spark can easily ignite this gas.
Determine if battery was connected or missing.
Examine the electrical system making certain that fuses,circuit breakers, and fusible links were operating correctly.
Examine fan, generator, and air conditioner belts, asthese belts are seldom destroyed in accidental fires.
Check for missing motor accessories indicating thatvehicle was inoperable, thus diminishing many accidentalfire causes.
Examine the carburetor to determine if it caused the fire orwas merely an exposure of the fire (newer vehicles maynot have carburetors).
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i. Vehicle fires other-than automobiles.
Recreational vehicles and trailer-mounted boats are usually offiberglass construction and may add to the fire load and firedamage.
Additional hazards of these type vehicles may be related topower generators, cooking appliances, or bilge areas.
The presence of auxiliary fuel tanks may tend to alter normalburn patterns making the cause of the fire more difficult todetermine.
Establish if different types of fuels are present at fire scene whichmay also alter burn patterns.
Vehicle registration and Ownership.
Make note of the vehicle license plate or other descriptiveindicators.
Attempt to locate VIN (vehicle identification number) which isusually located on or near the dashboard.
Check the glove compartment for paperwork which may aid inestablishing ownership or detailed information about vehicle.
D. Wildland
Fires in open land covered with grass, brush, or timber are often termedwildland fires. Although they are often terrifying in their destructive power andintimidating in their coverage, they begin, like almost every other fire, withsuitable fuel and a small, localized source of ignition. All fire investigationsrequire thorough and systematic examination of the suspected area of originand logical and analytical assessment of the evidence found. Wildland fires areno exception.
The fire personnel who understand fuels, fire behavior, and the effects ofenvironmental conditions are in a better position to interpret the subtle andsometimes delicate signs of fire patterns in wildland fires, and therefore arebetter able to identify the origin and cause, no matter what type of fire isinvolved.
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1. Fire behavior
a. Fire not influenced by strong wind will usually burn uphill in afan-shaped pattern (“V" pattern).
b. In the uncommon circumstance of a strong, downhill wind, the firewill burn down the hill only to the degree that the ambient windcan overcome the fire's tendency to burn uphill.
c. On level ground, in the absence of a wind, fire will spread fromthe center in all directions but its spread will be inhibited by thewind it creates, blowing back into the base of the fire from alldirections. Such a fire will spread very slowly.
d. Ambient wind will modify the patterns by adding an additionalspreading component, so that the fan shaped pattern on thehillside will deflect to one direction or the other and apredominant direction of travel will be created on level ground.
e. In a fire having an extended perimeter, the direction of burningmay vary locally in almost any direction depending on theinterdependence of the terrain, the air currents created by the fireitself, and the ambient wind.
f. Fire travel is controlled by weather, wind, fuels, and topography.
g. As with structure fire investigation, no single indicator will identifycause and origin of a wildland fire. Several indicators must beidentified and used to trace fire travel back to the point of origin.
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2. Burn indicators
a. Charring of a tree trunk, plant stem, or fence post is deeper onthe side facing the oncoming fire. Char depth can be checkedwith a knife blade, pencil point, ice pick, or screwdriver. It isstrictly a comparative indicator, so absolute depth is of littleconsequence. Tree trunks and fence posts may have beensubjected to prior fire, so take that into consideration.
CHAR DEPTH DEEPER ON SIDE FACING FIRE
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FIRE FIRE
b. Destruction of a -bush or tree will be more extensive on the sidefacing the fire.
FIRE TRAVEL
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c. The beveling effect of a fast fire may influence the appearance ofbranches or twigs remaining upright. Twigs and branches facing the firemay be flat or rounded stumps while those facing away from it(downwind) will be tapered or pointed.
FIRE TRAVEL
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d. A fast- moving fire creates a draft around large objects whichcreates an angled pattern around tree trunks, posts, plant stems,and the like.
FIRE SPREAD
FIRE SPREAD
e. A slow-moving fire, especially one that is "backing" against the wind ordown a slope, will create a burn pattern approximately level with theground. Note that such patterns can be influenced by local fuel loadsuch as needles, leaves, and debris around the base of the tree.
FIRE SPREAD
FIRE SPREAD
f. If the vertical stem is burned away, the remaining stump will bebeveled or cupped on the side facing the fire. This will be trueeven for stems or weeds.
FIRE SPREAD
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g. When the back of the hand is brushed lightly against suchstubble, the beveled tops will allow the skin to pass smoothlyacross in the same direction as the fire but resist with sharppoints a hand passing in the opposite direction'.
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SMOOTHFIRETRAVEL
ROUGH
h. Rocks, cans, signs, and other non-combustibles will provide abarrier to the flow of the flames and show greater heatdiscoloration on the side facing the fire. Lichen, moss, andclose-growing grass may survive on the side away from the fire.
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FIRETRAVEL
i. Tall weeds and grass, when burned by a slow-moving fire(particularly as it backs along the flanks) will be undercut by thefire moving along the ground. The stems, if vertical, will then falltoward the fire with the heads of grass stems pointing backtoward the fire origin. This effect is highly dependent on the windconditions prior to and during the fire. Tall grass that is alreadymatted down pointing away from the fire will fall in that direction,so there is often conflicting directions from such indicators.
j. The height of remaining stems and grasses is roughlyproportional to the speed of the fire. The effect is dependent onthe moisture content of the plants and will not be visible in areasthat have re-burned.
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FIRETRAVEL
k. In the immediate vicinity of the origin, the fire will not havedeveloped any particular direction and the indicators will beconfused or contradictory. Fuels in the form of grass or weedsmay still be upright or only partially 'burned in the immediate areaof origin.
l. Extension of a fire beyond a barrier, for example, a road or river,will cause the appearance of a brand new origin. This isparticularly true when the "new" fire is started by airborne embersor burning debris from an established fire rolling downhill(sometimes called "spot fires").
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3. Determine the Area of Origin
a. Utilize firefighters and witness statements to determine the areaat which the fire was first observed.
b. Depending on the nature of the terrain and the extent of the fire,a fan-shaped or V-shaped pattern may be visible from a shortdistance away. The apex of this pattern can then be selected asthe focal point for the search pattern.
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LATER DEVELOPINGSTAGE
STARTSEARCH
TYPICAL“V” PATTERN
c. Identify burn indicators and work backward to identify the area oforigin.
d. Take into consideration the wind direction at the time of the fireand the relative humidity.
e. once an area of origin is located, rope it off This will controlaccess to the area and limit damage to the physical evidence.
f. Conduct a slow and systematic search of the area of origin todetermine the source of ignition.
4. Sources of Ignition
a. Unattended fires or fires inadequately extinguished by campers,hunters, and others.
b. Carelessness with smoking materials, including burning tobaccoand matches. Cigarettes may not ignite dry vegetation unless therelative humidity is under 22%.
c. Trash burning and, in some areas, controlled grass and brushburning.
d. Sparks from vehicles, especially locomotives or othermotor-driven equipment.
e. Heat and/or fragments from a disintegrating catalytic converter.
f. Lightning, which is a major cause of timber fires.
g. Power transmission lines and accessories such as transformers.
(1) Transformer short circuits and malfunctions
(2) Leakage over dirty insulators and supports
(3) Fallen wires
(4) Arcing between conductors
(5) Grounding of in-place conductors
(6) Birds coming in contact with conductors
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h. Arsonists generally- use a lighter or match, but may use a varietyof devices, i.e., road flares, matchbook devices, etc. Look formultiple points of origin.
i. Firearms, which under certain circumstances may blow sparks ofburning powder into dry vegetation.
j. Spontaneous combustion, limited to very specific types ofcircumstances.
k. Overheated machinery which may be in contact withcombustibles.
l. Miscellaneous objects, sometimes present among trash, includingglass that can focus the sun's rays (burning glass effect).
m. Sparks from any source, such as, impacts of metal with rocks orstatic discharge.
n. Fireworks and/or explosives igniting dry vegetation or woodshingles.
5. Evidence
a. Identify human and/or animal travel in the area.
b. Photograph fire scene and the burn indicators that lead to thearea of origin.
c. Photograph footprints and tire tracks.
d. Identify evidence of haste in leaving the area.
e. Evidence of area use by humans.
f. Evidence of accidental fire cause.
g. Evidence of incendiarism: flares, device remains, placement oftypes of fuels, multiple points of origin and accelerants.
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h. Evidence collection:
(1) Use proper containers.
(2) Photograph all evidence prior to picking up.
(3) If possible, sketch the scene and the location of theevidence.
E. Explosions
An explosion is defined as the sudden and rapid escape of gases from aconfined space, accompanied by high temperatures, violent shock, and a loudnoise.
To clarify, an explosion is the result of an unstable compound or conditionreturning to a more stable condition with great speed. It will be accompanied bythe release of energy, heat, light, and noise.
Two pressure waves result from an explosion. The first is positive wave which isthe force of the explosion travel away from the center of the explosion in alldirections. second or negative pressure results from the first and is air rushingback toward the center of the explosion to the to fill the vacuum created by thepassage of the positive wave. The negative wave has about 60 percent of thepower developed by the positive wave.
When responding to a possible explosion, keep alert as the scene isapproached. The clues to look for in an explosion are any physical evidence offorces exerted on the structural components of the structure. This could includebroken glass or debris from the structure located some distance from theinvolved structure.
Having determined an explosion has occurred, the next step is to determine theorigin of the explosion.
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1. Types of explosions
a. Mechanical
A mechanical explosion is any explosion that occurs within acontainer or vessel. This. type of explosion must involve anunstable physical condition which consists of pressure on oneside of the container and a pressure on the other side of thecontainer that is higher or lower. This condition might only occurfor a millisecond as in the case of a pipebomb.
b. Chemical
A chemical explosion is caused by the rapid conversion of achemical compound into gases. This compound may be eithersolid or liquid. The conversion takes place in an extremely shortspan of time and is accompanied by shock waves, a loud noise,and high temperatures.
c. Nuclear
A nuclear explosion occurs within the atom of an element andmay be either nuclear fission or nuclear fusion.
2. Common sources of explosions
Gases - natural gas, sewer gas (methane) , LPG, and other flammablegases.
Flammable Liquids - gasoline, solvents, cleaning fluids, and otherlow-flash point flammable liquids.
Dusts - combustible metal, agriculture material,plastics, and carbonaceous dusts.
Unstable or explosive chemicals.
Steam, air and electrical explosions.
Explosives and blasting agents - commercial types of dynamite and TNT,bombs, and improvised explosive devices (IED).
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3. Indicators of accidental-explosions
Types of explosions and their indicators depend on what caused theinitial explosion.
a. Natural gas
Depending on the amount of natural gas that fills the structurebefore it reaches a source of ignition will determine the amount ofdamage. Natural gas will travel from room to room filling all areas.Because it is lighter than air, it will travel upward until it reachesan area that is blocked. It will continue to fill the structure evenflowing into a basement area or sub-floor. It often finds its wayinto sewers, pipe chases, and tunnels. It will continue in thismanner until it dissipates or reaches a source of ignition.
You will frequently find the structure bulging from all sides wherethe explosion has traveled from room to room. You might findexternal walls blown outward with interior walls still intact. Thisphenomenon occurs due to the pressure being equal on bothsides of the interior wall at the moment of the explosion.
Since natural gas is lighter than air you will normally find theupper portion of the structure more heavily damaged than thelower areas.
A natural gas explosion will not always cause a fire.
b. Liquid petroleum gas
Liquid petroleum gas such as butane and propane are heavierthan air and tend to seek lower levels in structures such asbasements, sub-floors, and crawl spaces. The walls of a structurewill frequently be blown outward from the bottom floor plate orsub-floor.
Another danger of LPG is that when its container is heated, it issubject to a B.L.E.V.E.. This usually occurs from direct flameimpingement on the container.
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c. Gasoline
Gasoline vapors are heavier than air and tend to flow along atfloor level. If a source of ignition ignites the vapors, the resultingexplosion will usually blow out the lower portions. of the structuredepending on the amount of vapors present. You will usuallyhave a fire after a flammable liquid explosion.
d. Dust explosions
Under favorable conditions, a dust explosion can occur in anyindustrial occupancy where combustible dusts are created andallowed to accumulate. Many materials are innocuous whenintact, but become explosive when finely divided to dust.
Almost all dusts are explosive with the exception of sand, rock,earth, and similar materials.
In some ways dusts are more violent than flammable liquidvapors. vapors are usually dissipated by normal air currentswhere dusts seem to settle and build up throughout the interior ofa structure. Consequently, a very small explosion may dislodgethe dust and put it into suspension throughout the interior. Asecondary explosion may occur and cause much greaterdamage.
The probability of a dust explosion is directly related to the type ofbusiness and the structure involved. A dust explosion would tendto cause damage throughout the interior as opposed to onespecific area. This type of explosion will not necessarily result in afire.
e. Backdraft
A backdraft is the rapid combustion of flammable gases that havebeen heated above their ignition point. This condition developsdue to insufficient oxygen. It usually occurs during the smolderingphase of a fire as oxygen is introduced into the confined space.
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A backdraft condition can usually be recognized by the heavy,thick, yellow/gray smoke puffing out of the structure with little orno signs of flame. As entry is made, a whistling sound can beheard as air is sucked into the structure.
f. Boilers and water heaters
These explosions occur when the internal pressure becomes toogreat for the container. There will not normally be a fire andevidence of the container should be found. Examine thecontainer as it should show signs of an internal explosion.
g. Electrical vaults and transformers
The location of the incident itself should lend some clue as to thesource of the explosion. An example would be where anexplosion occurs in an underground vault. You might find thesteel cover completely lifted off and some distance away from thevault.
4. Indicators of criminal explosions
When responding to the scene of a possible explosion, approach thescene carefully. Conduct a preliminary examination and attempt todetermine the source of the explosion.
If an explosive device (pipebomb, etc.) is found or it is determined theexplosion was caused from an explosive device, follow the proceduresoutlined in the Fire Department Manual of Operations.
Pipebombs are the most common type of Improvised Explosive Device(IED). The container can be common galvanized pipe or PVC plasticpipe which is being used with more frequency.
Pipebombs are usually filled with either black powder or smokeless gunpowder. These powders are a low order explosive (3000 feet per secondor less velocity). The shattering effect is much less than found in highorder explosives (3000 feet per second or greater velocity).
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Low order explosions can- usually be recognized by the non-shattering,pushing type effect. Walls appear to be pushed outward, ceilings areraised, and windows and doors may be intact even though they areblown out of their frames.
A black powder pipebomb explosion will usually leave black carbondeposits in the area where the bomb or device was placed. Thefragments of a pipebomb will usually be long, ripped-type fragments.
High explosives devices - typical high explosives are Nitroglycerin, TNT,Dynamite, Military C-3 and C-4 plastic explosives. High explosives havea shock wave of approximately 25,000 feet per second.
High explosives shatter nearby windows and even windows at a greaterdistance. Walls will be blown out and fragmented. Debris will be found insmall pieces at a great distance from the scene. There may be a craterwhere the device was located. The device will shatter and fragment intovery small sharp-edged pieces.
5. Safety at the scene of a bombing
A bomb scene is an extremely dangerous area. The possibility of asecond, unexploded device must be considered. In recent years,numerous bombing incidents have been complicated by the presence ofa secondary device designed to detonate at such a later time as to injurepolice and fire department personnel.
The chance of undetonated explosives remaining in the immediate areapresents imminent danger. Downed power lines, gas leaks, weakenedstructures, and other bomb devices also pose potential danger topersons at the scene. The Incident Commander should expend everyeffort to secure the scene and protect the evidence.
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IV. CAUSE DETERMINATION
A. Elements of a Fire Cause
All fires must be investigated. A critical fact to keep in mind is that all firesshould be considered ACCIDENTAL at the beginning of each investigation.Examination of the fire scene will either confirm the accidental nature of the fireor will establish circumstances to the contrary. An arsonist's main line ofdefense rests with the possibility of an accidental cause. As a result, effortsmust be made to rule out all reasonable causes for the fire.
There are three main elements involved in the determination of every fire cause.These elements include Heat, Fuel, and an Event which brings the two together.
1. Heat
Heat energy can result from:
a. An exothermic (heat-producing) reaction between fuel and anoxidant where "heat" is one of the products of combustion.
b. Spontaneous heating when characteristics of certain materialscause a heat-producing reaction with or without exposure to anexternal heat source. This process can exist as a straightchemical interaction (such as sodium metal with water), a processof oxidation or a fermentation (known as "thermogenesis").
Some common substances subject to spontaneous heating are:alfalfa products, charcoal, fish oils and by-products, and certainmetals in fine particle form.
c. Electrical activity such as:
(1) Overcurrent
Heat buildup in insulation adjacent to wiring.
(2) High Resistance Fault and material
Heat buildup caused by imperfect electrical path such asfrayed wires or poor points of contact.
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(3) Arcing/Sparking
Heat buildup caused by an arc, where a spark travelsacross a gap. This is a normal occurrence in an electricaldevice, where the glowing particles are confined within theunit. If this happens in an extension cord, a fire mayresult.
(4) Lightning
The discharge of electrical energy from a cloud to anopposite charge on another cloud or the ground.
d. Mechanical activity
(1) Frictional Heat
The mechanical energy used in overcoming the resistanceto motion when two solids are rubbed together.
Example: a drive belt slipping against the surface of apulley.
(2) Friction Sparks
Resulting from the impact of two hard surfaces, one ofwhich is usually metal. Depending on the metal, thetemperature of these sparks can range from 500 to over2500 degrees Fahrenheit, normally above the ignitiontemperatures of flammable materials.
Example: a tool striking the surface of a concrete floorand causing sparks.
e. Heat of Compression
Heat energy released when a gas is compressed. Temperature ofa gas will normally increase when compressed.
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f. Nuclear activity
Heat energy is released from the nucleus of an atom along withpressure and nuclear radiation. In the process of nuclear fission,energy is released by splitting the nucleus of an atom. In nuclearfusion, energy is released by the joining of two nuclei. The energyreleased by nuclear means is commonly a million times greaterthan the energy released by an ordinary chemical reaction.
2. Fuel
The ignition of a fire is dependent upon:
a. Mass (amount) of the fuel
b. State of the fuel
(1) The fuel can consist of any solid material such as woodproducts or plastics.
(2) Fuel can be in the form of a liquid such as any flammablefluid, either acting as a primary fuel or as an accelerant.
(3) The fuel can be in gaseous form such as hydrogen gas,methane gas, propane etc.
3. Event
An event which brings the heat source and the fuel together can be:
a. an Action (Acts)
b. a Lack of Action (omissions)
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B. Accidental Fire Causes
1. Electrical
a. Introduction
Electricity is blamed for being the cause of many fires onlybecause it may be present in a suspected area of origin.Electricity is capable of, and responsible for, causing fires.However, its mere presence at the area of origin is not sufficientto allege it is responsible for the fire. A thorough investigation ofthe electrical system in question must be undertaken tocorroborate or eliminate the probability of an electrical failure.
b. Basic Electricity
All matter is composed of molecules which, in turn, are composedof atoms. The atom is the building block of matter. An atom iscomposed of a positive nucleus (protons and neutrons)surrounded by the negative electrons which rotate around thenucleus of positive charges in the same manner that the planetsrevolve around the sun in our solar system. To comprehendelectricity, an understanding of the following terms is essential.
c. Definitions
ELECTRON - The very small negatively charged particles whichare practically weightless and circle (orbit) the nucleus of anatom.
FREE ELECTRONS - Electrons that have left their orbit in anatom and are wandering free through a material.
ELECTRIC CURRENT - The movement of free electrons.
POSITIVE CHARGE - A deficiency of electrons.
NEGATIVE CHARGE - A surplus of electrons.
CONDUCTORS - Materials that permit the free movement ofmany electrons such as silver, copper.- aluminum, zinc, brass,and iron (listed in order of ability to conduct).
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INSULATORS Materials that do not permit the free movement ofmany electrons such as dry air, glass, ceramics, mica, rubber,and plastics (listed in order of their ability to insulate).
POTENTIAL (VOLTS) - The ability of a source of electrons toovercome resistance. As compared to a water system, it would bewater pressure.
CURRENT (AMPERES) Rate at which electrons pass through acircuit. As compared to a water system, it would be gallons perminute.
RESISTANCE (OHMS) - Opposition offered by a material to theflow of current. As compared to a water system, it would befriction loss.
POWER (WATTS) - Rate of energy use or dissipation. Theproduct of POTENTIAL x CURRENT (115 volts x 1 amp = 115watts).
DIRECT CURRENT - Current that always maintains a direction ofelectron flow.
ALTERNATING CURRENT - Current will periodically change thedirection of electron flow (regulated at 60 times per second in theUnited States).
FAULT - A partial or total failure in the insulation or continuity of aconductor.
GROUND FAULT - An insulation failure between a conductor andground, where the failure is not to a grounded conductor normallyintended to carry current in the circuit.
SHORT CIRCUIT - A fault where there is an abnormal connectionbetween two points of different voltage in a circuit. A short circuitoccurs between conductors that are intended to carry currentunder normal operating conditions.
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d. Types of Electricity
(1) Static Electricity
Static electricity means electricity at rest on the surface ofa body as distinguished from the commonly recognizedtype of electricity known as electricity in motion.
The terms are primarily used to describe effects, such asthe sparks observed when one walks across woolcarpeting on a dry day and touches a metal object. This iscompared to the completely different effects of electricityin motion which are the production of heat and light andmagnetic forces such as used to drive electric motors.
Static has also been known as frictional electricity since itis generated by rubbing or contact and separation of thesurfaces of two dissimilar bodies. When sufficient chargehas accumulated, a spark or electrical discharge may beformed. It is this resulting spark which often causes theignition of flammable materials.
Any process that involves the storage and handling offlammable gases and liquids, combustible fibers anddusts, and similar easily ignitable materials can be subjectto the fire hazard of static electricity. Although there is nogeneration of static electricity in the actual storage offlammable liquids, static charges are produced during theturbulence in mixing, flow, or discharge of liquids orgases. Sparks from static charges occur more frequentlyin the dry winter weather than in the hot, humid months ofsummer.
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(2) Current Electricity
Electrical energy is transferred through conductors bymeans of the movement of free electrons that migratefrom atom to atom inside the conductor. Each electronmoves a very short distance to a neighboring atom whereit replaces one (or more) of its electrons by forcing it out ofits outer orbit. This continues until the movement ofelectrons has been transmitted throughout the length ofthe conductor.
Current electricity may be generated in various ways. Oneway is through the use of an electric generator. In thisdevice, a magnetic field is brought near a coil of wire.
As long as the magnetic field is changing, that is, the coilor magnet is in motion, a current will be produced in thecoil.
Another way of setting electricity in motion is by the use ofchemical energies in an electrical cell (a group of cells iscalled a battery).
If we wish to have the electrical energy do useful work, wemust provide an appropriate electrical path for the currentto flow through. In this respect, it is similar to a watercircuit. If we want to do something with water, we musthave a path to pass it through (a pipe) . Voltage can bethought of as the electrical pressure forcing the electronsthrough the circuit and current as the electron rate.
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Any time a current of electricity is flowing, a magnetic fieldwill also be generated. A magnetic field is developedaround any wire carrying an electric current. If the wire iswound into a coil, the magnetic field will be concentrated.This is the basis of an electromagnet. Whenever aconductor is moved through a magnetic field, an electriccurrent will be generated in the conductor. An electricgenerator works on the principle that a coil of wire movesthrough a magnetic field.
An electric motor is exactly the opposite. A coil of wire isin a magnetic field in the motor. When a current is sentthrough the coil, there is a magnetic field produced by thecoil in the opposite direction to the magnetic field normallypresent in the motor. This causes the motor to rotate.
The design of a circuit can be such that one of theseeffects (heat or magnetism) can be made greater than theother, but we can never completely eliminate any one ofthem.
In electric heaters, the purpose is to convert electricalenergy into as much heat as possible. We have no use for the magnetism which is produced.
However, it is present around the heating coils as well asaround the conducting cable. In an electric motor, thedesired product is magnetism, heat being undesirable.
The electrons passing through a conductor constantlycollide with other electrons. This causes heat to beproduced. The greater the current, the more heatproduced. If the size of the conductor is undersize, it canbecome very hot and become a possible ignition source.
Some materials are better conductors of electricity thanothers. In other words they will transmit electrons betterthan other materials.
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Metals are generally considered to be good conductors ofelectricity. On the other hand, materials such as glass,stone, plastics and synthetic textiles resist the flow ofelectricity, and as nonconductors, are used as insulators.
(3) Conduction Heating
The heating of conductors used to convey current isnegligible under ordinary circumstances. The codes limitthe current a conductor can carry and therefore theamount of heat generated. This limit depends upon thesize of a conductor, its composition, and the type ofinsulating covering. Where these limiting currents areexceeded (where a conductor is overloaded), thegeneration of heat may become a hazard.
A small overload has only a minor affect on overheatingdue to the "built-in" safety factor. For instance, a 30ampere fuse used instead of a 20 ampere size is a 50%overload, but even with this amount of overload, sometime would be required to feel the temperature rise of theconductor.
Extension cords are easily overloaded because they areusually small in diameter and rated for less ampacity thanthe service they are plugged into, such as an 18 AWGlamp cord plugged into a 20 ampere receptacle circuit.Careful examination for signs of entrapped heat will beindicated where identification labels are around the cord,or where the card enters the plug. If the condition existsfor a long period of time, the insulation will becomeseparated from the wire conductor.
Consider the situation where a small #18 AWG extensioncord is plugged into an appliance circuit protected at 20amperes. In case of a short circuit in the extension cord,possibly from frayed or cracked insulation, the current hasto be 400% of rated value for the breaker to function (#18AWG rated at 5 amperes).
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This could cause overheating of the extension cord. Thecircuit feeding the receptacle would not be overheatedsince, if properly insulated, it would have been #12 AWGand rated at 20 amperes.
Conduction heating heats the full -length of the wire all theway back to the box. Extreme overcurrent can cause thewires to reach fusion temperature and when the initialpoint fuses, an arc can form. If the insulation becomesdestroyed first, the resulting bare wires will touch and arc.
When these things occur inside metal boxes or conduit,the failures are usually trapped and of little concern.However, if the failure has sufficient energy to burn a holethrough the metal enclosure, a fire may result. Frequently,the examination of the wiring in an unburned area canprovide useful information such as its age and generalcondition. If it is older and the insulation has becomebrittle and cracked, electrical problems should beconsidered.
If a section of undamaged wire between the suspectedarea and the supply can be found, the condition of theconductor can provide some useful information. If theinsulation and wire are in a new condition with notarnishing of the conductor, it would be unlikely thatovercurrent occurred to the degree where ignition hadtaken place. Electrical arcing, however would still havebeen possible under these conditions.
When an electric current flows through a single circuitpath, the current (amperes) is the same in all parts of thecircuit. The temperature at any point is dependent on theelectrical resistance at that point and also upon the ratethat heat can be transferred away. Referring back to theprevious example, the #18 AWG wire has a higherresistance per unit length than the #12 AWG. Therefore, itwill operate at a higher temperature.
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Heating of electrical wires also occurs from loose or poorlymade connections and terminations. Cords under rugsand carpets or cords left coiled up, entrap heat causinginsulation overheating with subsequent degradation andpossible failure. 1
(4) Contact Resistance
In order to act as an ignition source, whether it be byovercurrent, sparks, or arcs, there must be a flow ofcurrent.
AN ELECTRIC CIRCUIT HAVING VOLTAGE SUPPLIEDTO IT BUT NO CURRENT FLOW WILL NOT CAUSEIGNITION.
When current flows through a circuit, heat is producedthroughout the circuit in proportion to the resistance at anyparticular point.
The current flow through a circuit is inversely proportionedto the resistance: the greater the resistance, the less thecurrent flow. The total resistance of a circuit determinesthe current flow (at a certain voltage) and thus the totalrate of heat production (watts). The distribution of theresistance throughout the circuit determines where theheat will be concentrated.
The points of high resistance can be where a portion ofthe conductor size is smaller, where the conductormaterial is different (as in an electric heater), and atconnection points (ends) where poor electrical contact orsplices are frequently made. Good practice calls for thelatter to be made in protective enclosures.
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In order to minimize heat buildup at connections, the following ismandatory:
The full cross-sectional area of the conductor bemaintained.
Positive contact of the conductors be maintained. Thismeans that no oxide or other film or foreign materialappears between the conductors.
An example of the first case would be the use of theinexpensive "zip" cord plugs that are installed by merelypushing the cord into a slot in the opened plug and thempushing it back together. The connection into the wire ismade by needle-like points being pushed through theinsulation and into the conductor. The cross-sectionalarea is diminished at this point and if used for anythingother than perhaps a clock or small lamp, excessiveheating can occur.
e. Residential electrical systems
Almost every residential building in the United States has apotential of 230 volts service. The electrical power enters thestructure through three wires. One of the wires is connected toearth by a ground rod or metallic water system. Because it is thesame potential as the earth, it is called the grounded conductor orneutral.
The voltage of the other two conductors has a potential from thegrounded conductor of 115 volts. The potential between the twoungrounded conductors would be 230 volts.
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The incoming power flows through the service entranceconductors to the watt-hour meter which monitors and recordsthe amount of electricity used. The current continues to flow intothe main service panel which may be a circuit breaker or fusepanel. To this point, no over-current device protects the serviceother than the primary utility company fuse which is calibrated toprotect the transformer windings from overload.
The power passes through the main circuit breaker or fuse whichmonitors the total power and protects the service equipment fromoverload. From here it is divided into separate smaller sub-panelsand/or circuit breakers or fuses to feed branch circuits whichsupply lighting, receptacles, and appliances. A 15 or 20 ampdevice protects general loads and higher rated devices are usedfor fixed loads such as electric ranges, air conditioners and waterheaters.
Complete building circuits consist of:
Overcurrent protective device such as circuit breakers orfuses in a panel or box.
Conductors (branch circuits).
Switches and/or receptacles.
(1) Overcurrent protective device
The conventional wall outlet receptacles are energized byan ungrounded and a grounded conductor to provide 120volts power between the two parallel blades. Theungrounded (hot) conductor supplying a wall outlet isprotected by a fuse or circuit breaker that protects thewires in the wall supplying the outlet. The rating of thefuse or circuit breaker is usually 15 amperes or 20amperes depending on the size of the wire routed to theoutlet. The fuse or circuit breaker is designed so it willoperate in the event there is excessive current in theungrounded conductor such that the wire insulation will beoverheated.
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It is important to note that a fuse or a circuit breaker hasan inverse current-time operating relationship. This meansthat the higher the current, the more rapid the operation. Afuse or circuit breaker protecting an outlet is designed toprotect the wiring in the wall from being overheated.
Consequently, the fuse or circuit breaker will carry itsrated current indefinitely but will actuate in less than 1hour at 125% of rating and in less than 2 minutes at 200%of rating.
A 15 ampere circuit breaker can carry 30 amperes for upto two minutes and be within specifications.
Because of the high values for operating current, fuses orbreakers offer no primary protection from electrical shocknor can they prevent fires from high resistance or arcingfaults. Lethal currents are on the order of 0.1 amperes,well below fuse or circuit breaker operating points, whilefires can be started at currents well below 15 amperes.
THE FUSE OR CIRCUIT BREAKER CAN BE EXPECTED TOPROTECT THE WIRING IN THE WALL - NOTHING MORE.
(2) Conductors
The heat produced within a conductor is dependent onthe resistance and the current flow. The size requirementsof a conductor depends upon temperature, size, andmaterial.
Types of Material
Insulation quality basically is dependent on the type ofmaterial and its thickness. In addition, importantconsiderations are its ability to withstand elevatedtemperatures and moisture. Wire insulation usuallyencountered are rubber, plastic, and asbestos. Othergood insulating materials are glass and ceramics.
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Conductors are, generally made of copper or aluminum.Solid wires are used in the smaller sizes and for purposesnot requiring flexibility. Larger sizes and wires needingflexibility are constructed of multiple strands of smallerwires.
Wire inside a metal conduit will rarely short circuit exceptwhen the insulation is destroyed by external heat. If itdoes short, the arcing is generally retained inside where itcannot cause ignition. of course if the arcing burnsthrough the conduit, it can then cause ignition of nearbycombustibles.
f. Temperature considerations
How high a temperature can be tolerated? This is dependentupon the rate of heat generation. The temperature must remainbelow the point where the conductor will melt or be otherwisemade ineffective. It also must be below the temperature wherethe insulation will be damaged.
(1) Insulation Rating
All building wire will have the code printed on the coveringor jacket of the wire or cable. Common building wire israted for continuous service at 140 degrees F. maximum.
“T" Thermoplastic 140 degrees
"R" Rubber 140 degrees
"H" Higher Temperature 167 degrees
"HH" Higher Temperature 194 degrees
(2) Insulation Color
Bare or Green Grounding Wire
White Neutral (Grounded) Wire
Black Line (Hot)
Other Colors Line (Hot)
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(3) Size Considerations
The conductor must be of sufficient size to bemechanically sound. A small appliance may require only avery small current, but a very small wire might be toofragile and break.
The conductor must be of such size so voltage drop is notexcessive. Generally, size must be adequate to supply theload without exceeding a 2% drop in voltage.
Allowable Ampere rating of Common Copper Wire
Wire Size Amperes Field Gage
18 stranded 516 solid 10 1 dime14 solid 15 1 penny12 solid 20 1 nickel10 solid 30 2 dimes08 7 strand 40 2 pennies06 7 strand 55 7 #14 AWG
(4) Receptacles, Switches, and Plugs
Wall outlet receptacles installed after 1962 haveprovisions for two parallel blades and a "U" groundingblade on the attachment plug. The larger parallel bladereceptacle is connected to the white (grounded) conductorat the silver colored screw on the receptacle. The smallerparallel blade is connected to the ungrounded (hot)conductor at the brass colored screw. The "U" groundingblade of the receptacle is grounded by a green or barewire or by the grounded conduit.
The three blade attachment plug used to energizeequipment provides 120 VAC between the two parallelblades in the receptacle when plugged into a receptacle.The equipment "U" grounding blade on the plug isconnected, by a green wire, to all exposed metal parts onthe equipment. Under normal conditions, there is nocurrent in this equipment grounding blade.
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In the event of an insulation failure in the equipment suchthat the exposed metal parts of the equipment come incontact with an energized conductor, the equipmentgrounding conductor provides a path for the electricity sothere will be sufficient current in the energized conductorto actuate the fuse or circuit breaker protecting the hotconductor. The equipment is thus de-energized.
The equipment grounding conductor plays no part in thenormal operation of the equipment, but it is an importantsafety feature. Without the equipment groundingconductor, a fault in the equipment, such as an energizedconductor coming in contact with the exposed metalsurface, may or may not cause the fuse to blow or thecircuit breaker to trip. it would depend on whether therewas a high or low resistance path to ground from theexposed metal part.
The chief hazard associated with switches is the arcingproduced when the switching device is operated. Manyswitches are either so designed or are enclosed tosafeguard against this hazard.
When an electric circuit which is carrying current isinterrupted either intentionally as with a knife switch, oraccidentally, as when a contact at a terminal becomesloose, an arc is produced. The intensity of the arcdepends in a great measure on the current and voltage ofthe circuit. If the temperature of the electric arc is high,any combustible material in its vicinity may be ignited bythe heat.
An electric arc may not only ignite combustible material inits vicinity, such as the insulating covering of theconductor, but may also fuse the metal of the conductor.Hot sparks from burning combustible material and hotmetal are thrown about and may set fire to othercombustible material.
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g. Conducting the investigation
Regardless of where the fire started or where the area of origin islocated, all suspected electrical failure investigations shouldalways start at the electrical service entrance. ALWAYS CHECKTO SEE IF THERE IS MORE THAN ONE SERVICE! Beabsolutely certain power is shut off to all services.
The size or ampacity of the service should be known. Theservice' voltage should be known. Determine the main fuse orcircuit breaker rating.
Because all power used in the building enters through the serviceequipment, examination of the service panel should give yousome idea if over-fusing, overloading, or other types of abuse arepresent. Alterations or additions to the electrical system usuallybegin at the service panel. Always check for doubling up ofcircuits such as more than one wire under a terminal screw. Notethe wiring method used from the service or distribution panel.Some, types are nonmetallic sheathed cable (Romex), armored(BX), knob & tube, thin wall (TW) conduit, rigid steel conduit, orplastic conduit.
Check for workmanship to see if it is a professional installation orthe work of a handyman. Handyman work is sometimes indicatedby flattened or kinked metal conduits, nails instead of straps tosupport conduit, overfilled or crowded wires in conduit, or Romexstaples drawn tight into cables damaging the insulation.
Check how splices are made in junction boxes. Check ifgrounding wires are just twisted together or are they fastenedunder a grounding screw. Are there covers on all electricalpanels, junction boxes, switches, and receptacles?
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(1) Examination of overcurrent protective devices:
Fuses of too large capacity or circuit breakers with toohigh a setting.
Circuit breakers made inoperative by blocking or taping ofthe tripping element (old type).
Plug fuses which have blown and in which pennies havebeen inserted or the metal of the fuse-holder has been cutback or in which a wire has been inserted.
Cartridge fuses which have blown and nails, wires, orother metal have been inserted.
Refillable fuses in which additional strips have beenplaced.
Fuses or circuit breakers in poor mechanical condition.
Fuses without enclosures in the vicinity of combustibles.
Doors or covers of fuse-cabinets removed or open.
Corrosion of fuses, circuit breakers, or enclosures.
(2) Examination of wiring
Uninterrupted runs of wire or cable rarely cause firesunless the wire or cable has been damaged. Checkplaces where a nail or leg of a staple may have beendriven into the insulation or areas of sharp bends.
A common cause of wire failure is abrasion against asharp edge where the wire enters or leaves an electricalbox or equipment.
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Over the years, some fire scene investigators haveaccepted the presence of balled conductors (beading) asprima facie indications of electrical arcing. Actual burningtests have demonstrated such symptoms occur normallywithout the necessity of electric current. Therefore, firescene investigators should show extreme caution inreporting the presence of balled conductors as symptomsof electrical arcing.
Close examination of the questioned wire usually willprovide useful information. The conditions of melting fromexternal fire heat are different from those of electricalarcing. When wires melt from external fire heat, there isusually only a small temperature difference between theparts that have melted and the unmelted sections. In thissituation, the wire section has been raised to the firetemperature and only a small number of additionaldegrees are needed to produce the balled or pointedsymptoms. By contrast, when wires are subjected toarcing, the wire section is at ambient temperature whilethe arc is at many thousands of degrees. The twodifferent situations are quite discernible by examination.Of course, as with other things, there are gray areaswhere both have occurred and also situations where hightemperatures have left the wire in such poor condition thatthe indications have been minimized or destroyed.
(a) Heat exposure
As copper wire is fire heated, there are changes.First, oxidation produces discoloration. As themelting temperature is reached, blistering andbubbling occurs from degassing. During melting,the striations caused by the manufacturing processflow together and there is a general flow of themolten copper resulting in balling and showingareas of erosion with a rough surface.
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When the wires are orientated in a vertical position, themolten copper can run down to a ball and then it drops offand leaves a pointed end. When the ball remains, theportion immediately above it shows a reduced diameterwhere the metal flowed from. There is no sharp line ofdemarcation showing points of melting and non-melting.Stranded wires flow together and form a solid mass.
Sometimes the strands are discernible but they have beenfused together and are not separable. Often several wiresinside a common conduit will fuse together. Thesesymptoms will be seen whenever a fire has attained themelting temperature. Usually it is localized since themelting temperature is slightly above the usual firetemperature.
The condition of wires frequently attributed to electricalarcing i.e., areas showing drop-shaped, balled andpointed formations, are most often the result of localizedheating where some locations along the wire haveattained a higher temperature than others. The meltingtemperature of copper is listed as 1981 degrees F. whichis somewhat above the average temperature of a typicalfire. In other words, the copper wire during a typical fire isslightly below its melting temperature. In this condition asmall localized area of higher temperature, such ascaused by an electrical arc, a concentrated fuel leak, orpossibly optimized combustion conditions results inlocalized melting of the copper wire as previouslycharacterized.
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(b) Electrical faulting
Electrical arcing, by contrast, does not usuallyresult in random melting, erosion, fusion ofstrands, and other symptoms indicative ofnon-localized heating. The characteristic ofelectrical arcing is the formation of a sharpdemarcation line between the arcing area and theunmelted wire.
Stranded wire exhibits the individual strandsimmediately to the point where the arc occurred.
When energized wires make contact and thecontact is not a secure connection, such as twobare wires touching without any mechanicalpressure, an electrical arc is usually formed. Itsmagnitude and duration will depend on theovercurrent protection (fuses or breakers) ,capacity, and the physical conditions under whichthe wires contact each other.
If the resulting arc is not confined inside a suitableenclosure, the high temperature of the arc canreadily ignite surrounding combustible materials.This is sometimes referred to as primary arcing.
Very frequently, however, signs of electrical arcingare not indicative of electrical ignition since mostwire insulation materials in general use arecombustible. Many times arcing is the result ofwires touching as a result of the insulationdestruction by the fire and while the appearance ofthe wire remains indicates arcing, the arcingactually was a result of the insulation degradationof the fire rather than the ignition cause(secondary arcing).
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(c) Melting v. arcing (helpful hints):
Electrically Caused
Insulation no longer bonded (burned internally)
Pitting of wire or connector
Metal splatter near fault
Fire Caused
Insulation tightly bonded (burned externally)
Melted wire with pointed end
Necking down of wire
Usually electrical, sometimes Fire Caused
Balling of copper at end of wire
Melting of conductors
Fusing together of wire strands
(d) Hazards associated with wiring systems.
Corrosion of the metal covering or enclosures ofconductors.
Covers of outlet or junction boxes removed.
Corrosion or loosening of supports.
Conductors of "open-wiring" systems separatedfrom their supports, in contact with each other, orin contact with pipes, woodwork, or otherconducting or combustible materials.
Conductor insulation deteriorated from age ormechanical injury, or from exposure to heat,moisture, or vapors.
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Conductors overloaded.
Joints not properly soldered, taped, or otherwise made.
Wiring installed for temporary use and not replaced.
(3) Examination of connections, receptacles and switches.
Hazards most likely to be found:
Pitting or burning of contacts at points wherecircuit is made or broken.
Overheating due to poor contact oroverload.
Corrosion
Enclosures removed or not effective.
Loose wire to terminal connections.
h. Evidence handling
When examining or securing evidence, if wires are connected toscrew terminals of any kind, it is better to cut the wires rather thanattempt to unscrew the screws as fire embrittled plastic insulationwill be damaged. Stagger the cuts so that you can reconstruct theevidence if necessary.
i. Summary
As in other investigative fields, it is especially true in theinvestigation of a suspected electrical fire, that common sense isa major asset. It is the improper installation and use of electricitythat makes it dangerous. A fire scene investigator should beknowledgeable in the basics and be able to examine the wiringremains and determine if it is adequate and make somejudgement of its conformance to good wiring practice..
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Tracing an electrical system in a burned structure can be atedious and time-consuming task. While any portion of the wiringremains might yield useful information, the most fruitful placesare where connections are made. This includes the serviceentrance box and other fuse and breaker boxes, the switches,receptacles, and, fixtures. Particular attention should be given tohigh current circuits such as heaters, stoves and dryers. Whenpart of the structure is undamaged, an examination of this wiringwill tend to show the condition of the wiring before the fire.
In addition to a thorough scene examination, a great deal ofinformation can be obtained from interviews of witnesses,occupants, owners, and equipment operators. Had there beenany recent repairs, modifications, or installations of any type tothe electrical system(s)? Had other types of repairs or work notassociated with the electrical system been done that may haveinadvertently had an affect on the electrical system?
Had there been any unusual odors, flickering of lights, circuitbreakers that continually tripped or fuses that requiredreplacement? Did all electrical appliances operate efficiently andproperly?
Traditionally, as in other fields, fire scene investigators have usedcertain criteria for judging electrical fire symptoms. Unfortunately,some are not as reliable as once believed. Some are outlinedhere:
Ignition by slightly oversize fuse or breaker.
When a slightly higher-rated fuse or breaker is found thanthe rated capacity of the wire, it probably is not the firecause. Current carrying capacities are conservativelyrated.
Balled wire ends.
This condition can be the result of fire melting, as well asfrom electrical arcing.
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Loose wire insulation (sleeving).
If the insulation is loose, it probably is from overcurrent. Ifit is not loose, overcurrent should not be ruled out. Theparticular type of insulation should be tested to determineits thermal changes.
Open circuits causing fires.
There must be a flow of current for ignition. Mere voltage(potential) on wiring will not cause ignition. There must bea current flow (amps). These forms can be short circuit,overload, insulation degradation, etc.
Energy
Was there sufficient electrical energy (heat) present tocause ignition of the surrounding materials?
Arcing - cause or result.
Did the arcing cause the fire or was the arcing the resultof wires touching that had their insulation burned off bythe fire?
Is the suspected failure consistent with the burn patternsregarding area of origin and subsequent firedevelopment?
Remember that common sense has no substitute. Thereare no magic potions or cookbook answers. Only ideasand guidelines that hopefully can guide the fire sceneinvestigator.
2. Cigarette caused fires.
In recent years smoking related fire deaths have accounted for nearly athird of all residential fire deaths where the cause of fire was known.Seven of every eight smoking related fire deaths where the form ofmaterial ignited was known, involved upholstered furniture, mattresses,or bedding. No other types of fires come close to accounting for thislarge a share of the residential fire fatality problem.
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The term "careless smoking" as a fire cause is much overused by firepersonnel.
Legislative history:
1973 - Legislation was passed requiring that any mattress sold inthe United States be-cigarette resistant.
1975 - Requirement that every piece of furniture sold in Californiabe flame retardant and smolder resistant. In 1980, thisrequirement was made more restrictive.
Most upholstered furniture (chairs, sofas, etc.) and mattresses are madewith cover fabrics and porous stuffing materials whose ignitiontemperatures (500-700 F.) may be easily exceeded by burningcigarettes. Some upholstery cover fabrics resist cigarette ignition betterthan others. Wool, nylon, olefin, polyester, and various other syntheticplastics generally melt rather than smolder.
Cotton, linen and blends of these fibers (cellulosic fabrics) will ignite fromburning cigarettes and smolder
Leather will also smolder and silks will not.
Filling materials used in upholstered furniture and mattresses consists ofcotton batting, urethane foam, foam rubber and polyester orcombinations of these. Cotton batting and foam rubber can easily beignited by burning cigarettes. Urethane foam and polyester will meltunder the heat of a cigarette and usually will not ignite. However, undercertain circumstances, urethane foam covered by upholstery fabric canbe ignited (smolder) and even burst into flames.
Such an occurrence might take place in a crevice of a chair or sofawhere a foam cushion exists next to a vertical side arm. A smolderingcigarette in this location may easily start a fire.
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In filling materials, cotton batting is easily identified as is polyesterfiberfill. Determining whether a foam material is rubber or urethane canbe accomplished by a simple match test by igniting a small piece ofmaterial, extinguishing it and smelling the odor of the residual smoke.The two classes of materials give off distinctive and different odors andthe identity of the :sample at hand can be obtained by comparison withknown foams. If these are not available, foam rubber will smell ofburning rubber and polyurethane foam will have a "sweet" odor.
Whether a cover fabric is cellulosic or synthetic (plastic) may bedetermined by applying a match to a sample of the fabric and observingwhether it melts, chars or flames. If on extinguishing the flame, a glowingpersists, then the fabric is cellulosic (cotton, rayon, linen or blends). If thefabric melts and drips, it is synthetic, for example: polyester, olefin, ornylon. Wool will not sustain combustion from a low heat source and willgive off a pungent odor similar to the smell of burning human hair.
If the fire cause is suspected of being associated with careless smoking,determine the following:
Were smokers in or did they have access to the area prior to thefire?
Determine if there is evidence of ash trays, cigarette packages,matches or lighters.
Try to determine the manufacture date of the furniture.
Smoker type fires typically take from 20 minutes to two hours to developinto the free burning phase. During the development of the fire, heavyproducts of combustion are formed. The fire begins as the heat sourcecomes in contact with the fuel. Smoke will begin to develop and moveupward as the burning continues. As an oxygen regulated fire, it burnsslowly and poorly.
The heat generated by a smoldering cigarette can vary greatly.Temperatures can be as high as 760 F. measured on the outside of theglowing ash, and 1440 F. measured in the center of the glowing ash.
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Depending on such factors as brand and freshness, cigarettes cansmolder for as long as 30 minutes. Cigarettes in contact with mostcombustibles usually result in localized charring and extinguishthemselves.
To initiate a smoldering fire with a cigarette, a form of insulation isusually required. This will allow the heat to build up and increase surfacecontact. A cigarette falling between a sofa cushion can produce therequired insulation.
Exception: Cigarettes in open contact with cotton bedding can result insmoldering followed by open flame combustion. One layer of cottonbedding placed over a cigarette will increase the smoldering tiptemperature by 100 F.
The cigarette must be in contact with a material capable of supportingsmoldering ignition. Dense cellulosic fabrics are most dangerous withrespect to a smoldering ignition source. Many smoking/ smoldering firesoccur in upholstered furnishing, bedding and draperies. The upper layerof material on a piece of furniture acts as an insulator, keeping the heatinside the furniture and regulating the flow of oxygen.
Heat is directed downward to the floor and floor damage beneath thefurniture is common. Normally this is an area protected from firedamage. Interior temperature increases until temperatures of 2000 F.may be reached. Springs and other metal parts may lose their temperand become annealed. The interior of the piece of furniture becomesmore badly charred than the exterior.
When the fire reaches the exterior of the piece of furniture, theavailability of oxygen is increased.
The time required before open flaming combustion occurs may vary with:
The type of material coming into contact with the cigarette.
Physical arrangement of the piece of furniture.
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Cigarettes in contact with flammable liquids or gases.
Cold ash around burning tip may act as a flame or flash screenthus inhibiting its ability to ignite the material.
Ignition may occur when an individual attempts to light a cigarettewith either a match or lighter.
Note: Under laboratory conditions, the Bureau of HomeFurnishings has never successfully ignited either flammableliquids or gas when a cigarette was used as the ignition source.
Cigarettes as an ignition source of dried vegetation.
Often overused as an ignition source.
The moisture content of the air and surrounding vegetation mustbe taken into consideration.
Burn patterns of the smoking/smoldering fire are:
Fire taking a long time to develop.
Large amounts of products of combustion (smoke) in and aroundthe fire scene.
Annealed springs in furniture.
Fire damage to floor below furniture.
Damage to interior of furniture greater than the exterior.
Indications of fire patterns leading back to a piece of furniture.
3. Other causes
Without exception, simple principles apply not only to special types offires, but to all ordinary fires. The source is some type of flame, spark, orhot object. In every case, the temperature of the source must be inexcess of the ignition temperature of the fuel with which this sourcecomes in contact.
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a. Low temperature ignition
Low temperature ignition can occur when heat as low as 212degrees F. is applied to cellulose materials over a long period oftime. This can occur in areas where combustibles are locatednear light bulbs or fixtures, steam pipes, flues,, or otherlow-temperature heat producing appliances. The low heatconverts the material to pyrophoric carbon.
Pyrophoric carbon results when the constant low-temperatureheat source, for example a steam pipe, over a long period of timelowers the ignition temperature of the surrounding wood until itassumes the characteristics, and sometimes the appearance ofcharcoal, which is notorious for its spontaneous heating qualities.
Indicators of low-temperature ignition are:
Large charred section of combustible material.
The presence of a low-temperature ignition source.
The discoloration or baking of the materials.
b. Light fixtures
Improperly installed lighting fixtures may cause fires in adjacentcombustible construction material such as joists, studs, insulation,etc. The fire may be slow starting and characteristic of lowtemperature ignition. There may be deep charring or pyrophoriccarbon in the area of origin.
In fluorescent fixtures, ballasts have a starting voltage of from700 to 900 volts and operate at about 400 volts. Thetransformers are designed to operate continuously atapproximately 194 degrees F. Presently manufactured unitscontain a thermal overload switch which is designed to disable itin the event of overheating. overheating of the ballast can meltand vaporize the pitchblende sometimes igniting combustibleceiling material.
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c. Light Bulbs
In evaluating light bulbs as a heat source there are threeconsiderations:
The wattage of the bulb, the shape or design of the bulb, and theposition of the bulb.
The following illustrations show the surface temperatures oflamps in various positions:
100 Watt Bulb
446
214
127
120
293
131
126
477
280
138
151460
194
181198460
271
172
208
228
300
191
162
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Examine the diagram of the surface temperatures of lamps invarious positions. Incandescent light bulbs may cause fires bycoming in contact with combustibles.
An overturned lamp may permit direct contact between a bulband paper, cloth or wooden surface, but unless the heat from thebulb is confined, it will dissipate and only charring to the exposedsurface will result.
Check for heavy smoke staining on the bulb fragments. Check forcombustibles stuck to bulb fragments.
500 Watt Bulb
241
113
109
291
117
113
536
291
124
128495
239
151160540
298
217
588
174414
239
203
167
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d. Motors
Motors, in addition to the windings, have moving parts. Somehave centrifugal switches which operate when the motor attainsoperational speed. Also, some motors require electricalconnection to the moving part (armature or rotor) which isaccomplished by brushes riding on a moving contact.
Electric motors present numerous possibilities for ignition. Theseare mainly overheating from excessive current due to defectivewindings or excessive mechanical load which prevents attainmentof proper operational speed, and sparks from the centrifugalswitch or brushes. These hazards may be overcome byconstruction of the motor frame so electrical parts are suitablyenclosed, or by keeping combustible material away.
The starting equipment of a motor presents hazards through thearcing and sparking of current-breaking contacts and through theheat produced in some forms of starting equipment. The hazardsof overloading a motor may be overcome by proper overcurrentprotection.
Examination of motor remains can frequently provide usefulinformation. When electric motors are found to be in a fire areanear a suspected point of origin, a thorough evaluation should bemade to determine if the fire was deep seated in the windings orif damage resulted from heat conducted to windings from fireoutside the motor housing.
If the shaft is frozen (will not turn) , it is an indication the heat wasinternal. If the motor was running during the fire, indications ofbits of solder in the interior of the motor housing are sometimesfound in motors having a commutator. Friction is indicated if themotor belt is most heavily damaged where it passes over pulleys.if immediately after a fire the motor housing is too hot to touch,but iron or steel of similar size in the same area is relatively cool,it could indicate interior heating of the motor. A stalled motor, orone which is not running up to speed, will overheat fromexcessive current.
This could be caused by numerous things: defective motor, tightbearings, too small a motor for the purpose, frozen or tight load,etc.
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When an electric motor from a fire is completely charred inside, it doesnot always indicate the motor was faulty. It could also indicate anoverload condition or that something caused jamming and prevented themotor from turning. If the motor was able to operate with the loadpartially jammed, the fire could have been started from friction of thebelts or pulleys. Fires from electric motors can also be caused bybearings that were not lubricated, faulty starting mechanisms, orexcessive dirt in the motor.
Fire hazards common to motors include:
Located too close to combustible material, which may be ignitedby arcs or sparks.
Location in a damp place, or where subject to corrosive vapors.
Lint or dusty condition of surfaces.
Burning out, which may be due to overload, stalling of the rotor orin some cases, too low voltage at the motor terminals.
Improper over-current protection.
Starting equipment that produces arcs and which is located tooclose to combustible material.
Check for a frozen motor shaft. If the motor has bronze bearings,a frozen shaft often results from internal heating.
Friction of the motor belt is indicated as a probable cause if thebelt is most heavily damaged where it passes over the pulley. Afire from another source will damage the belt most where it isunprotected by the pulleys.
Check for evidence of motor wiring insulation having burnedextensively.
Check for proper motor installation and overload of fuses orbreakers.
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e. Transformers
Electrical motors and transformers have a similarity in that theycontain magnet wire that is wound on an iron core. Both canoverheat from excessive current flow. This excess can causeinsulation destruction which, in the absence of proper overloadprotection, is capable of causing ignition.
Fire problems with transformers have similarities to motors.However, the mechanical functions and high starting currentconditions are not applicable. Some electronic equipmentcontaining transformers have been known to start fires becauseof the absence of proper fuse selection by the manufacturer.
f. Televisions
operating television sets, even the new solid state sets, candevelop considerable heat. Cabinets housing such equipment areprovided with ventilation openings at the rear and bottom.Installation of televisions into other cabinets or recessed intowalls may produce excessive heat build-up. Dust can also buildup inside the set which may produce arcing and cause ignition ofplastic components. Many televisions operate at up to 32,000volts in some areas within the set.
Failure of these high voltage components may cause extremeheat and ignition. Prior trouble with the set may be an indicatorpointing to the set. Try to determine if the set was recentlyworked on Check for extensive floor damage under the set. Thistype of fire could produce results similar to furniture fires.
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g. Electric blankets and heating pads
Electric blankets have been responsible for some fires. Thecause of these fires can often be attributed to misuse. Blankettemperatures are controlled by a thermostat usually located at theedge of the blanket. When blankets are partially covered withadditional blankets or other materials, it is possible for theseareas to become overheated. If the main control switch is left on"high" in a cool room, the current could remain on continuouslyand cause the covered section of the blanket to overheat.
Blankets have been known to cause a fire when tucked betweena mattress and padded box spring.
It can be difficult to determine whether a bed fire was caused bya blanket or other cause such as smoking in bed unless the firewas detected early and the char path traceable. Sometimesblanket remnants containing the thermostat and control willindicate if the blanket was turned on.
Fires caused by electric blankets are frequently due to misuse bythe owner. Manufacturers instructions and safe use require thatblankets are not to be covered by other bed coverings, or foldedor tucked under mattresses. If the blanket was left bunched orpiled in one spot, enough heat could build-up to ignite themoisture resistant envelope and in turn the fabric itself.
h. Appliances
Many small appliances have thermal controls, thermostats, and/orcurrent overload protective devices. If small appliances such ascoffee makers, irons, deep fryers, frying pans etc. are suspected,check the bimetallic thermal controls or contact points. Thecontact points often become carbonized or dirty through use andwill not completely close, which causes an arc.
The arc in turn causes pitting or sticking, sometimes fusing. Thisallows overheating.
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Some manufacturers -have historically been lax in providingproper overcurrent protection. Rectifiers have been known to failand cause power transformers to overheat and cause theinsulation to ignite for the lack of proper protective fuse orbreaker. Most household electronic equipment is low powerapparatus, but situations do occur that have not been anticipatedby the designer.
Properly used quality appliances in good working condition willnot normally start a fire.
When examining appliances, observe the flow patterns of meltedaluminum or plastic. The direction of flow may indicate theorientation of the object at various temperatures. Plastic melts atapproximately 800 F aluminum at 1100 F., brass at 1725 F., andcopper at 1980 F.
i. Heating equipment
Heating devices come in a variety of shapes, sizes, and types.Electric, gas, oil, coal or natural gas heaters are commonthroughout the country. These appliances could become a firecause for three reasons: (1) improper installation, (2) humancarelessness, and (3) a mechanical malfunction.
Improper installation is increasingly common. The lack oftechnical and mechanical knowledge leads to many improperinstallations. Check for proper clearance, ventilation andinsulation. Compare the situation to manufacturer's instructions ornationally recognized standards.
Look for the human factor such as allowing combustible materialto accumulate too close to the heating device. Sometimes peopleput clothing directly on a heating device to dry the clothes.People may use the wrong type of fuel for the particular heatingdevice.
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Mechanical malfunctions are a rare occurrence because of thesafety factors built in to all appliances. However, check the firebox, pipes, flue and controls. Check for excess soot (carbon)which may indicate incomplete combustion. Check for electricalshort circuits in the controls. Check for tool marks.
A word of caution to the fire scene investigator: When anyappliance is suspected of being the cause of a fire, be sure youhave investigated carefully. Even the least experienced arsonistwants the fire to appear to have a logical accidental cause.Flammable liquids could be poured around the heating device.Examine all fittings as well as the burn pattern on the floorcarefully.
j. Cooking equipment
Consider the point of origin in respect to the cooking equipment.The point of origin is usually on or over the unit. However thepoint of origin could be over a sink if the occupant attempted tomove and extinguish a burning pan.
The point of origin on the kitchen floor may indicate the occupantattempted to remove the burning pan but dropped it. Personalinjury is common.
Check for evidence of food preparation. If the fire is an accidentalfire which ignited during attempts to cook food, there should beevidence of food preparation. Check the time factors. Did the fireoccur at normal mealtime?
Check the position of the burner/oven controls. Even though thecontrol knobs could be burned away, you should be able todetermine the position of the controls by examining all of them.
Question the occupants. Remember, no one likes to admitresponsibility for a fire, particularly where extensive damageresults.
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Look for proper installation, clearances from cabinets, trashcontainers, etc. Look for tool marks, missing cover plates and/orscrews that could possibly mean recent maintenance ortampering.
k. Flammable or Combustible Liquids
Flammable and combustible liquids do not "cause" fires. They arecontributing factors. A spark or some other ignition source causesa fire or explosion in the presence of flammable vapors. Improperuse and storage are the most common "contributing factors"when flammable or combustible liquids are suspected of being atthe point or area of origin and the first to be ignited.
Flammable liquids are of ten improperly used as a cleaning fluidin washing machines, carpet cleaners etc. Lightweight plasticcontainers used for liquid storage may become brittle with ageand may be punctured easily by a sharp object. The liquid itselfmay deteriorate the container over a period of time. Glasscontainers break easily. Metal containers may rust or deterioratealong the seams and slow leaks may develop.
Flammable liquid vapors usually settle to the lowest level in theinvolved area. Vapors can come in contact with an ignition sourceand flash back over long distances. Some of the most commonignition sources are water heaters, stove/ranges, and electricalequipment such as light switches and motors.
The following indicators may point towards a fire involvingflammable or combustible liquids:
Cleaning equipment found at or near the area of origin.
Low burning and heavy charring.
Evidence of rapid flame spread.
Evidence of an explosion followed by fire.
Statements of the occupants.
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1. Fireplaces
If the fire originated in the attic or roof, check the integrity of the fireplaceflue construction. Check for leaks in the chimney. Check for proper sparkarrester installation.
Try to identify the residue of the ashes in the fireplace. Was the properfuel being used? Was it recently cleaned out? Did the occupants attemptto accelerate the fire?
Examine the damper and determine if it was open or closed. Try todetermine if furniture or other objects were placed too close to thefireplace. Radiated heat can start fires.
If you have a roof fire without evidence of a fire in the fireplace, checkaround the neighborhood for other fireplaces which could be emittingsparks or embers.
Chimney fires occur because soot, dust, cobwebs, and a variety offlammable materials are allowed to accumulate in the chimney wherethey may be ignited by a spark from the fire below resulting in a largeblaze within the chimney itself. Large quantities of burning debris may beexpelled onto the adjacent roof or roofs, causing ignition.
m. Open flames and sparks
The most obvious heat source is open flames such as matches,candles, furnace and stove pilot lights, trash fires, etc.
(1) Matches
Matches are the most common device for starting a firewhether its purpose is to ignite the barbecue or ignite theforest. Examination of partially burned paper matchesmay establish it came from a particular matchbook.
(2) Lighters
Lighters generally ignite liquid fuel with a spark from anabrasive and steel. Lighters are an obvious substitute fora match. They are rarely left behind.
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(3) Candles
Candles can often be an accidental source of ignition,particularly during the holiday season since they are usedprimarily for decoration. The lack of a proper base cancause a problem as well as vibration, wind or other factorswhich may cause a candle to fall over and ignite anycombustibles in the area. Candles have often been usedto set fires because of the advantage of a delayedignition. Candles generally leave a deposit of wax.
(4) Sparks
A spark is an incandescent (glowing or hot) particle,thrown off from a burning substance or resulting fromfriction. An electric arc is a discharge of electric currentthrough air. A spark differs from, an arc in that a spark isusually instant and the arc persists for a longer timeinterval.
Sparks from welding, cutting, grinding, and friction frommachinery are common sources of ignition, especially in aflammable liquid vapor environment. These type fires areusually easy to detect because in most cases there ishuman activity involved.
(5) Pilot lights
Pilot lights in gas appliances such as water heaters,stove/range and gas heaters are a common source ofaccidental ignition especially when flammable liquids arebeing improperly used in the vicinity. Pilot lights havebeen responsible for numerous explosions and fires inclandestine drug labs since the chemicals used in makingthe drugs, such as ether, are highly flammable. Ether hasa flash point of -20 degrees F.
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The pilot light for any appliance is not in itself hazardous,but when combustibles and flammables are allowed tocome in contact with the flame, through carelessness,fires result Many times routine questioning of theoccupants will give the fire scene investigator the answerto what happened. Often the physical evidence will beobvious, such as the nature of the victim's burns, the opencan of cleaner, or evidence of a rapid intense flash burnof short duration.
(6) Trash and rubbish
Trash and rubbish fires are another common source ofaccidental fire damage to structures, automobiles andgrass/brush. Although trash burning is usually illegal,people will "take the chance", especially with the inflatedprices at local dump sites. This type of fire should beeasily identified by the fire scene investigator because itinvolves human activity. Trash fires can produce flyingembers and can start fires in other locations.
n. Natural Fire Causes
Spontaneous Heating
Spontaneous heating is the process by which a materialincreases in temperature without drawing heat from itssurroundings. Spontaneous heating of a material to its ignitiontemperature results in spontaneous ignition. Three conditionswhich have much to do with whether or not spontaneous heatingwill create a dangerous condition are (1) rate of heat generation,(2) air supply, and (3) insulation properties of the immediatesurroundings.
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In order for spontaneous ignition to occur, sufficient air must beavailable to permit oxidation, yet not so much air that the heat iscarried away by convection as rapidly as it is produced. An oily(vegetable oil) rag might heat spontaneously in a pile or in thebottom of a trash container but would present no problem if hungon a clothesline.
Additional or external heat can initiate spontaneous heating insome combustible materials not subject to this phenomenon atordinary room temperatures. In these instances, preheatingincreases the rate of oxidation sufficiently so that more heat isproduced than can be lost. Many fires have been caused by thespontaneous heating of foam rubber products after initial heatingin a clothes dryer.
Elevated moisture content or improper curing of agriculturalproducts has a definite influence on the spontaneous heating bybacteria.
C. Incendiary fire causes
As set forth in the CFIRS manual, an incendiary fire/act is defined as a firewhich is willfully and maliciously set (arson fire); unlawful fires (recklessly set);possession of flammable or explosive materials, and attempted arson.
1. Indicators of an incendiary fire (observations or circumstances depictingthe possibility that the f ire was intentionally set):
Multiple fires
Trailers
Presence of flammable accelerants
Absence of all accidental fire causes (negative corpus) .
Use of common equipment and/or appliances as a source of ignition.
Structural damage prior to the fire.
Contents out of place or contents not assembled.
Major appliances removed prior to the fire.
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Absence of personal items.
Location of the fire.
Evidence of other crimes in the structure.
Unnatural fire spread, excessive fire damage, or evidence of extremeheat.
Entry of fire companies blocked.
Windows or view into structure blocked.
Short period of time between exit of occupant or suspect and discoveryof fire.
Second fire in same structure.
Evidence of burned or unburned newspapers near point of origin.
Time of day
Fires during renovation
Reported activities of owners/occupant.
2. Accelerants
Definition -materials, usually a flammable liquid, that are used toincrease the spread of fire.
Flammable liquids (flash points below 100 degrees F.)
Gasoline
Readily accessible and most commonly used
Kerosene
Alcohol
Water soluble
Difficult to detect
Dissipates quickly
Lighter/charcoal lighter fluids
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The presence of a flammable liquid at a fire scene does not conclusivelyindicate incendiarism. Examples of accelerants normally found in homeor businesses:
Paint remover
Polish remover
Cleaning fluid
Alcohol
Printing fluids
Gasoline
Solvents
Examples of locations where common accelerants might be found:
Cabinets
Utility room
Workshop
Medicine cabinet
Garage
Search for residue or flammable accelerants in locations or places wheresuch liquids would not normally be stored. Examples:
On or in furniture
Inside drawers, cabinets, boxes and files
Over unusual areas or over wide floor areas
Indicators of the probable presence of flammable accelerants:
Charring of large areas of floor
Puddle-shaped floor char
“V" -shaped grooves burned between floor boards or elongatedholes burned through flooring in line with grooves betweenboards.
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Suggested locations to be searched for accelerantresidue:
Flammable accelerants may have soaked through flooring andburned beneath floor or on ground under the structure.
Open floor and check for accelerant residue between floor andsub-floor.
Lowest level of any floor is likely to collect most of theaccelerants in that area.
Low or worn areas such as high traffic areas, area aroundfurniture, and/or areas where heavy items rest.
Sweep and rinse floor, then slowly pour water onto floor. Waterwill settle in same areas where accelerants were puddled.
Flammable accelerants may soak into any absorbent material on or nearthe floor:
Carpet (leaves very distinct burn pattern).
Residue may remain in carpet and pad.
Check floor drapes for accelerant residue.
Unusual burning of contents and/or building components may indicatethe use of an accelerant:
Burning (char) on bottom edges of doors is unusual in mostaccidental fires.
The charring of the undersides of furniture may indicateflammable accelerants.
Burning of floor surfaces along edge at contact with walls may bedue to accelerants being present.
Corners and wall-to-floor edges are usually dead air spaceswhich suffer little, if any, fire damage unless flammable liquidsare present.
Flammable liquids may carry fire behind baseboard molding.Moldings should be removed and examined.
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Char patterns may indicate use of accelerants:
"Alligator char" (large pattern char) usually indicates a fast hot fire. Thisindicator should only be used when compared to the time and stage ofthe fire and the material involved.
Burning in a downward direction is usually considered to be unnatural.Flammable accelerants may have run and carried flames downward.Exception: polyfoam or other synthetic material may melt and run whileburning.
Residue of flammable liquids may be detectable by use of a flammable vapordetector.
Flammable liquid odors may be detected during fire extinguishment.
Flashback of fire during extinguishment may indicate presence of accelerants.
Discovery of flammable liquid containers may provide comparison sample forlaboratory analysis.
The flammable liquid container may provide fingerprints.
3. Incendiary Devices
Definition- a device which would assist an individual in the setting and possiblespreading of a fire. May also offer a time delay factor.
a. Firebomb (also known as Molotov. Refer to Sections 453 (b) and12303.3 Calif. Penal Code)
(1) Components
A breakable container, containing a flammable liquid with a flashpoint of 150 degrees Fahrenheit or less, having a wick or similardevice capable of being ignited.
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(2) Alternative mixtures
Gasoline and oil mix
Flammable liquid and soap flakes constitute a "napalm"mixture which adheres to the target.
b. Cigarette/Matchbook device
An ignited cigarette placed in the cover of a paper matchbookacting as a -time delay device.
c. Candles and combustibles
Materials are readily available and components are easilyprepared and may also act as a delay device.
d. Fireworks
Fireworks can be used as the basis for an incendiary devicewhen used in conjunction with accelerants or ordinarycombustibles.
4. Negative Corpus
Definition - the methodical elimination of all accidental (natural,mechanical, and electrical) causes.
Absence of all accidental f ire causes. Requires very detailed notes andreports. May be difficult to prove to the satisfaction of court or jury.
5. Trailers
Definition - any combustible or flammable material used to spread thefire from one point or area to another. Trailers usually leave char or burnpatterns on surfaces where used.
Floors
Steps
Aisleways
Through doors, windows, or wall openings.
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V. CONDUCTING THE INVESTIGATION
A. Conducting the Investigation
When compiling information relating to a fire scene investigation, theobservations of the first arriving Fire Department units can be a valuable sourceof information.
These observations, early in the fire extinguishment process, can assist the firescene investigator in knowing what had transpired prior to their arrival.
The following information should be obtained from those members who hadearly access to the fire and knowledge of the circumstances surroundingaspects of its early stages.
1. Receipt of alarm
The day of the week and time of alarm will often be the first indication ofpossible motive in an incendiary fire. outside fires between 1500 hrs. and1800 hrs. during weekdays are frequently the result of juvenile activityafter school. Late night/early morning fires in businesses on weekendsare frequently the result of fraud fires.
2. Observations enroute to the fire:
a. Weather conditions.
Is it hot, cold, cloudy or clear?
Are conditions in the involved structure appropriate for theweather?
If it's cold outside, you would expect to find the windows closed. Ifit's hot, the furnace should be found off.
b. Natural hazards.
Had there been lightning, flooding, fog or an earthquake?
Arsonists often wait for natural conditions which will delay the firedepartment's arrival at the scene.
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c. Wind direction and velocity.
Knowledge of these factors will aid in determining the naturalpath of fire spread.
d. Man made barriers.
Are there barricades, downed trees, cables or trash containersobstructing the fire departments arrival? These could be earlyindications of a suspicious fire.
3. Arrival at the scene:
a. Compare what is found at the scene with the information given toyou by the Incident Commander. In an industrial building, if thefire has developed greatly in intensity between the time of thealarm and the arrival of the fire department, it could indicate thepresence of an accelerant.
b. Were any cars seen speeding from the scene? If so, try to obtaina description/license number.
c. Dress and appearance of persons leaving the scene.
d. Were windows and doors covered? Drawing the shades orcovering the windows and doors with blankets are techniquesemployed by arsonists to delay discovery of the fire.
e. What was the Fire Department's means of entry? Were the doorslocked/unlocked, closed or open? Was there evidence of forcibleentry?
f. Observe the color of smoke/flame. This is often the firefighter'sfirst observation to the type of combustibles involved in the fire.Firefighters should be interviewed as soon as possible. Flamecolor can provide another clue for the fire scene investigator todetermine what is burning and the intensity of the fire.
4. While fighting the fire, be aware of:
a. Separate and seemingly unconnected fires.
b. The presence of usual odors. Some odors are likely to be familiarto firefighters. These include food, wood, grass, gasoline,kerosene, paint thinner, lacquers and turpentine.
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c. The presence of unusual odors.
d. Reaction of fire to water. A straight stream of water applied whereflammable liquids were used may cause the liquid to float to thetop, reignite, and continue to burn and spread the fire.
The presence of an accelerant may also be suggested byflashback and/or several rekindles in the same area or by anincrease in burning after water is applied.
e. Obstacles to hinder fire fighting. Was furniture moved in thepremises in such a manner as to make movement difficult duringfirefighting?
f. Artificial conditions created to assist fire spread. Arsonists oftenprop open fire doors, pull down plaster to expose wood, or punchholes in ceilings from floor-to-floor, or walls from room-to-room inorder to increase the rate of fire spread.
g. Absence of furnishings, clothing or personal effects. Absence offamily pets (birds, cats, dogs) in dwelling fires.
h. Absence of stock, fixtures, machinery, display cases, records orraw materials in industrial or commercial properties.
i. Uneven burning or localized heavy charring. Char on theunderside of doors, base boards, or on the underside of any lowhorizontal surface may indicate there was a flammable liquidpool. Fingers of char in the cracks of wood flooring can alsoindicate the presence of a flammable liquid.
j. Intensity of heat generated by fire. A very intense heat mayindicate an accelerant was applied to increase the fire spread.
k. Speed of fire spread. Taking into consideration the building'sstructure and occupancy, did the fire spread unusually fast? Anunusually rapid fire spread could indicate the use of anaccelerant.
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l. Tampering or damage to fire prevention facilities. Was thesprinkler system in operating condition? Were the sprinkler valvesopen before the fire? Was the fire alarm system in workingorder?
m. Tampering or damage to burglar alarm.
n. Was the burglar alarm set and did it activate? What was thenormal routine for setting the alarm?
5. After extinguishment:
a. For the safety of firefighters and to preclude re-ignition of the fire,a cursory examination by the fire scene investigator for origin andcause should begin immediately while the firefighters take abreak and pick up unnecessary hose lines and equipment. Checkto see that members did not destroy any incendiary devices orother evidence during extinguishment.
b. Note attitude and dress of owner/occupants. One would expect tofind the owner or occupants of a building distressed at anunexpected fire. occupants should also be found in attireappropriate to the time of day. If the fire occurs at 0400 hours, itwould be noticeably suspicious to find the occupants fullydressed.
c. Note individuals who attend several fires. Some arsonists areemotionally disturbed individuals who receive personalsatisfaction in seeing a "successful" fire. Individuals who attendseveral fires, especially in various locales, are suspicious.
d. Note any persons at the scene acting abnormally. Most personsat a fire scene are intent on watching the fires extinguishment.Persons at the scene constantly talking, laughing, or in any waymaking light of the situation, should be considered suspicious.
e. Record name, address, telephone number, and date of birth ofowner(s), occupant(s), and witnesses.
6. Follow these steps to determine the area of origin:
a. When you conduct your investigation, start with the exterior andproceed to the interior, from the least damaged areas to the mostor heaviest damaged area.
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b. Determine whether the fire originated at the building's exterior orinterior. Look for burned or smoked areas on the roof, doors andwindows.
c. Check for any openings that may have caused drafts to influencethe fire spread. If natural-gas might be involved, examine theoutside gas valve to see if it was on or off before the fire.
d. Examine the interior completely to locate the area/room of mostsevere damage and any other evidence that may have a bearingon cause or spread of the fire.
e. Check the floor, walls, and ceiling to find the worst area ofdamage. Often the point of origin can be found directly beneaththe worst area of damage on the ceiling.
f. Find the lowest point of burning within the area of origin. It maybe helpful to look under furnishings and shelves for severecharring. Examining the depth of char on wood can help todetermine both the length of burning and the point of origin.
g. Look for the direction of heat flow. After locating the area oflowest and deepest charring, look for other heat indicators. Lightbulbs may swell and lose their shape at 9000 F. when exposed toheat for 10 minutes or more. The side of the bulb exposed to thefire initially may melt and come to a point.
h. Examine the colors on chromium and other shiny metalssubjected to the fire (check surfaces of ovens, toasters, irons andother appliances). The progress of the fire can be traced bycomparing the color of various shiny metals at different locationswithin the area of origin.
i. Window glass in the immediate vicinity of the fire's origin willexhibit only traces of smoke while glass farther away from thefire's point of origin will reveal heavier concentrations of smoke.
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j. Look for evidence of multiple fires. Are the sources of ignitionindependent of one another? When a room reachesapproximately 1,000 F. a flashover may occur making the entireroom appear to burst into flames at once. Upon investigation,flashovers of highly combustible materials may lead the firescene investigator to suspect there were two or more separatefires.
k. As areas are examined and determined to contain no evidencepertaining to cause & origin and the area is deemed safe forfirefighters, limited overhaul operations may be initiated.Exception: fire scenes involving homicides, fire fatalities or otherrelated crimes.
l. Keep in mind, burning flammable liquids and combustiblematerials may cause heavy charring at locations distant from thesource of ignition and might not necessarily indicate the point oforigin.
m. Look for a definite fire pattern. A normal pattern is upward andoutward in a "V" shape.
7. Indicators of slow or fast-burning fires:
a. Overhead damage. Uniform overhead damage usually indicatesa slow, smoldering fire. Extensive damage in one place on theceiling indicates an intense, rapid buildup beginning below thisspot.
b. Fire pattern. A wide angle "V" pattern usually indicates a slowburning fire.
c. Crazing of glass. Large cracks and heavy smoke usually indicateslow burning while irregularly shaped cracks and slight smokefilm usually indicate rapid burning.
d. Alligatoring. A fast, intense fire will cause heavy alligatoring andshiny, smooth blisters on exposed wood surfaces. A longdeveloping, low heat source will produce flat alligatoring.
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e. Line of demarcation. Examine a cross-section of a piece of woodfound near the point of origin. A distinct line between charred andun-charred portions of the wood indicates a fast, intense fire. Agraduation in charring and an overall baked appearance usuallyindicates a long, slow fire.
f. Spalling. Surface pieces of concrete, cement or brick may breakoff when exposed to an intense heat source or when subjected toa high level of heat and cooled rapidly.
8. Determine the cause of the fire:
It may be easiest and most effective to locate the cause of the fire iffurnishings remain in their original positions within the area of origin.Remember, a fire needs both a fuel supply and a heat source. Fuelsinclude flammable liquids, combustible solids and combustible gases.Heat sources may include open flames, hot surfaces, electricity, frictionand reaction (spontaneous ignition).
a. Is there equipment in the area of origin that could have emitted aspark, overheated or backfired?
Be aware of low temperature or non-flaming heat sources likelight bulbs, electric blankets, electric irons or steam pipes, which,over a period of time, can ignite combustible materials they comeinto contact with.
If electric motors are found in the area of origin check the interiorof the motor windings to see if the damage was deep seated.
Motor burnout may also be indicated if, after extinguishment, themotor housing is too hot to touch but iron or steel of similar size inthe same area is relatively cool. If the motor was running duringthe fire, there may be bits of solder in the interior of the motorhousing. Friction as a fire cause will be indicated if the point ofdamage to the motor belts is worse where it passes over thepulleys (in fires from outside sources, belts are mostly damagedbetween pulleys).
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In electrical appliances having a thermal control, sticking or fusingof the contact points may cause overheating of the device.Electric clocks found in the debris can be extremely helpful. Theymay aid in determining the burning time, progress of fire, andinvolvement of other electrical. equipment in the area.
b. Was there any possible source of an electrical short circuit? Firstcheck the fuse panel for tampering. Is it overloaded with improperfuses? A short circuit or dead short will usually burn the face of aglass fuse while overloads or high resistance shorting will onlymelt the fuse band without burning the face of the plug.
It is difficult to tell whether a short circuit caused the fire or was aresult of the fire. Continued overload of a circuit will result indecomposition and carbonization of insulation on both sides ofwhere the short occurred. Shorts caused during the heat of thefire, however, may show beading but decomposition andcarbonization of insulation will be found only on the side exposedto the fire.
c. Were smoking materials involved? Cigarettes require goodinsulation in order to cause flaming combustion with an averageincubation or smoldering time of about 1-1/2 hours. Fires causedby cigarettes in furniture will be slow and smoldering, leavingheavy charring on the insides of the furniture and on the floor inthe immediate area. Long periods of smoldering will cause thecoil springs in the furniture to collapse (1400 F.) and may becomebrittle due to rapid cooling during extinguishment.
d. Were there any signs of an explosion? Gas leaks can causeexplosions, so check appliances and gas furnace valves to see ifthey were open or closed. Look for loosened pipe fittings andpiping sawed or cut in half. Take note of any gas appliancesfound in unusual locations.
e. Was spontaneous combustion a possible fire cause? Since ittakes a considerable mass of combustible materials to producespontaneous heating, some remains from the internal charringmay be found at the point of origin.
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Location is an important factor in considering the possibility ofspontaneous ignition, the materials necessary are rarely found inlarge quantities in living rooms or bathrooms. It usually requires agreat deal of time to produce the amount of heat necessary tocause spontaneous ignition.
Substances Active in Spontaneous Combustion.
Substance Form
Aluminum Shavings, filings, powder
Animal matter Hides, skins, manure
Bronze Shavings, filings
Magnesium Shavings, filings
Miscellaneous Sawdust, coal, flour
Steel Shavings, filings
Vegetable matter Hay, grain
Vegetable oils All
Zinc Shavings, filings
f. Combustible solids like wood, paper and rags can be found inmost buildings, but were they in a normal location?
g. Check the layers of debris one by one to determine the sequencein which things burned. Were there any newspapers found in anunusual place? If so, are the newspapers of different types ordates?
h. Checking the condition of burned wood can help to determine thelength of time of flaming combustion. Douglas fir and similar softwoods have a char rate of approximately 1" in 45 minutes whenexposed to fire temperatures of 1500 - 1900 degrees F.
i. Look for specific evidence of incendiary origin.
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j. Trailers between fires made of paper, string or cord soaked in oil,rope soaked in kerosene, dynamite fuses, black gunpowder,cotton batting and kapok, streamers, excelsior, or anycombination of these.
k. Candles used to ignite trailers. Was there residue of candle waxor paraffin near the point of origin?
l. Matches tied around combustible fibers or attached tomechanical devices.
m. Accelerant containers and evidence of flammable or combustibleliquids including gasoline, kerosene, solvents, alcohol, acetone,paint thinner and ether. Since flammable liquids flow to the lowestlevel, more severe burning found on the floor than on the ceilingmay indicate the use of an accelerant as floor temperatures areusually lower than ceiling temperatures.
n. If an accelerant has been used, charring may be as great orgreater on the bottom of furniture, shelves, doors, etc. comparedto the topsides of these items. If flammable liquids have soakedinto wooden flooring, there may be heavy burning at the jointsand ink blob outlines may be found after extinguishment. Sincemost floors are not completely level, look for heavy charring incorners. Accelerant residue may be found in the soil underbuildings with a raised foundation if an accelerant has been used.
o. Rags, clothing or curtains soaked in oil.
p. Rubbish and paper.
q. Timing devices including clock radios, timers and telephones.
r. Electrical equipment and/or appliances may be used to initiate afire or may be placed at the area of origin to make it appear as asource of ignition or cause of the fire. Was it plugged into anoutlet?
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VI. EVIDENCE
A. Types of Evidence
Evidence has been defined as all the means by which any alleged matter offacts are proved or disproved. It includes objects, testimony or statements,records or documents, and anything else that can be legally presented at a trial.Evidence can normally be divided into two major categories; direct andcircumstantial. Evidence can be briefly defined as "The facts that tend to provesomething."
When called to the scene of a fire, the Incident Commander's first responsibilityafter suppression is to determine the cause and origin of the fire. If theydetermine the fire was intentionally set, their concern shifts to the discovery ofevidential material that will support their contention and prove the elements ofthe crime of arson in a court of law.
Evidence can take many forms and it is up to the Incident Commander to searchout all areas of the scene to determine what is evidence and what is not.
1. Direct Evidence
Direct evidence is any evidence that directly proves a fact, without aninference or presumption on the part of anyone. Direct evidence wouldinclude physical evidence, eyewitness statements, and confessions. Agood illustration of direct evidence would be where a witness sees anindividual light a grass fire with a fusee. Both the statement of theeyewitness and the remains of the fusee would be direct evidence.
a. Physical evidence
This evidence has a physical substance or existence and can beperceived by any of the five senses (hearing, seeing, smelling,tasting, and feeling). It may be a burn pattern, ignition device,trailer, container of accelerant, remains of a fire bomb, or a faultyappliance or electrical component.
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b. Eyewitness statements
This type of direct evidence would be testimony of a witness'spersonal experience of hearing, seeing, smelling, tasting, orfeeling directly related to the facts being presented. This couldinclude a witness seeing an individual set a fire, a witnesshearing a threat being made, or a witness smelling gasoline in aroom prior to a fire.
c. Confessions
A confession consists of those statements, made by a suspecteither spontaneously or after their waiving of the Mirandaadmonition, implicating the suspect in the crime. The corpusdelicti (crime of arson) must be established independently of theconfession.
2. Circumstantial Evidence
Circumstantial evidence is evidence of an indirect nature. Circumstantialevidence is the proof of facts based on inference. Certain facts areproven and from these facts the court or jury may infer other facts whichwould normally follow based on common sense and experience.
Where the crime of arson is established by direct evidence, theconnection of an individual to the crime may be proven by circumstantialevidence and any reasonable inferences.
An example of circumstantial evidence would be where a businesssuffers an incendiary fire. The investigation reveals that business wasbad and the owner increased the insurance the day prior to the fire. Thepoor business and the insurance increase would be circumstantialevidence and along with other direct evidence could implicate the ownerin the crime.
3. Evidence Handling
After suppression and during the initial phases of cause determination,look for evidence indicating the cause of the fire or contributing factorswhich may have influenced the spread of the fire. Don't overlook theobvious such as items absent from or foreign to the immediate firescene.
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Handle all evidence with-care:
a. When possible, photograph the fire scene, emphasizing the pointof origin and any incendiary devices on the premises, makingsure to photograph devices exactly where they are found.
b. Leave all evidence intact if at all possible. Barricades may behelpful in blocking off the area to further foot traffic. Areassurrounding devices should be roped off and a guard should beposted to protect the evidence.
c. If in doubt of how to handle or preserve the evidence, contact theappropriate arson unit for instructions.
d. If an arson unit is requested, protect the evidence by preservingthe fire scene from overhaul and water additives. If the evidenceis out of the immediate area of the scene, place a firefighter toguard the evidence. Do not remove it or touch it if possible.
e. If no arson unit is requested, photograph evidence before movingit. Clean unused paint cans with lids that automatically seal whenclosed are the best containers for retaining evidence. Plasticcontainers and plastic bags should be avoided as any evidenceof petroleum products may deteriorate the plastic. Paper bagscan be used for dry clothing or metal articles, matches or papers.Either a cellulose sponge or cotton batting can be used to soakup small quantities of liquids.
f. All evidence should be marked in some way. Marking shouldinclude the date, time, location, officer's name and assignment.
g. Fire scene investigators should keep a record of each personwho handles the evidence.
h. Preserve the chain of custody in handling evidence. If the chainof custody is not preserved, the court may rule the evidenceinadmissible.
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i. Once evidence is found, preserve it, photograph it and make anote of where, when, and how it was found. Protect the evidencefrom contamination, alteration, damage, or destruction. Uponreturning to quarters, notify the arson section by telephone. Besure to include all information under the F-902 comment section(arson screen). Additionally, all information relating to the incidentand the evidence should be journalized.
j. Store the evidence in the station in a safe and secure location.Keep it in a place where "curious" firefighters won't handle it. Donot store evidence in an area accessible to the public. Requestarson to pick up the evidence as soon as possible. If theevidence is not collected in a reasonable time, notify the arsonsection again to determine when the evidence will be picked up.
4. Chain of Evidence
The term "Chain of Evidence" refers to the chain of custody (possession)of an item of evidence from the point in time when it was first discovereduntil the time it is offered as an exhibit in court. Any break in the chain ofevidence could preclude its use as evidence in future court proceedings.
Evidence can take many forms and it is up to the fire scene investigatorto search out all areas of the scene to determine what is evidence andwhat is not.
It takes evidence, both direct and circumstantial to successfullyprosecute and convict individuals responsible for the crime of arson. Beaware of everything in the area when conducting the scene investigationfor the cause and origin. Following these procedures should ensure thatwhen the evidence arrives for its "day in court", no problems will beencountered.
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VII. MOTIVES
A. Motive Types
Various types of fires can be more readily identified if the fire scene investigatorat the scene is aware of a possible motive for that fire. Being able to identify amotive can assist in developing a suspect for the fire.
1. Spite/Revenge
At this point in time, "Spite" is the most predominant motive that you mayencounter. It is most commonly found in domestic disputes.
Fire is frequently the weapon of someone who wants to be removedfrom the physical act of violence. A fire of this type is often the mostdeadly and can result in extensive loss of life.
a. These fires often occur in the bedroom and can be the result of aproblem in a personal relationship.
b. They usually occur during the hours of darkness.
c. They may involve the use of available combustibles, but are oftenset using flammable liquids as an accelerant.
d. Articles of clothing may be gathered in a pile to be burned.
e. A vindictive person may target a personal vehicle for an act ofvandalism.
f. Statements made concerning neighborhood disputes can be avaluable tool in establishing spite as a motive for your fire.
g. Spite fires may also result from an emotional conflict such as inwork relationships, labor disputes, racial confrontations orreligious antagonisms (hate crimes).
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2. Juveniles
"Juveniles" is not a motive, however, since this group is often involved inmany different types of fire-setting, it is listed here as a separate motivegroup.
a. Children have a natural curiosity about fire, usually occurring inboth sexes between the ages of 4 and 12.
b. INTENT is 'the primary consideration. If the child's intent wasNOT to set fire and/or if the act was intended as playing orexperimenting with fire, this incident should not be classified asincendiary.
c. Juvenile fires often occur in secret or hidden places such asclosets, under beds, basements and attics.
d. Juveniles occasionally set "nuisance" fires in trash and grass, theseverity depending on extension and intent.
3. Pyro/Psycho
"Pyromania" is defined as the uncontrollable impulse to start fires. Thismay or may not be connected to sexual gratification or desires. Thefollowing is a list of traits, some or all of which a pyromaniac maypossess.
a. A loner, a loser.
b. Unable to do anything about being a loser or a pyromaniac.
c. Suffering a setback of some kind.
d. May use alcohol/drugs to boost courage.
e. May be extremely deceptive.
f. Seldom carries an accelerant.
g. May set more than one fire at a given time.
h. May set fires in structures or outside.
i. Finds some kind of relief by setting fires.
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j. The fires usually occur in buildings other than their own.
k. The "pyro" fires usually set some type of activity pattern.
l. May or may not stay in the incident area after setting the fire(s).
4. Crime Cover
There are many reasons why fire may be used by a criminal. In allcircumstances where a fire may have been set to cover a crime, effortsmust be made to protect the scene.
a. A fire can destroy books/records in an effort to cover shortages ofstock, materials, cash, or other items.
b. A fire can destroy evidence of other crimes such as signs offorcible entry, fingerprints, rifled drawers, or other physicalevidence.
c. A fire may be set to cause a distraction so that criminal activitycan occur in other areas of a neighborhood.
d. A fire may cover evidence of a homicide or a suicide.
e. Another crime, such as burglary, can be staged by the owner toexplain a fire that has been intentionally set.
5. Fraud
By definition, a "fraud" is a deception deliberately practiced in order tosecure unfair or unlawful gain. There are several types of fraud fireswhich are usually encountered:
a. Direct gain fraud fires are frequently associated with:
(1) Collection of insurance money.
(2) Interruption of mortgage payments.
(3) Inability to dispose of unwanted property when taxes aredue.
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(4) A structure that is "condemned". It's cheaper to burn thantear down.
(5) Property is being divided in court. Estate settlementmoney is easier to divide.
(6) Periods of business recession (seasonal businessessuffer more incendiary fires than do year 'roundbusinesses).
(7) Merchandise/equipment becomes obsolete or out of style.
(8) Insurance money is of greater value than rent money.
(9) Owner's desire to redecorate/remodel.
(10) Dissolution of a business partnership.
b. Indirect gain fraud fires may or may not involve profit frominsurance money.
(1) Tenant sets a fire to break a lease.
(2) Landlord sets a fire to force tenants out. New leases bringincreased rent.
(3) Owner sets fire to competitor to reduce competition.
c. Organized criminal activity may include insurance fraud,elimination of competition, and fires set for purposes ofintimidation.
6. Vanity
a. "Profit Vanity" fires may be a form of indirect fraud. Example: asecurity guard or watchman may set one or more fires to securea raise in pay. Another example would be that of an "on-call"firefighter who seeks to secure their job position by setting andthen extinguishing fires.
b. "Hero Vanity" fires are incidents which many believe to be closelyassociated to some forms of pyromania. This would include a fireset by an individual who wants attention for finding andextinguishing the fires.
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7. Civil Disorders, Revolutions and/or Political Activity
In these cases, fire is often used as a weapon. it produces destruction ofproperty and creates the illusion a large group of people are involved infiresetting in a specific area.
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VIII. REPORTS AND RECORDS
A. Introduction
In the City of Los Angeles the primary responsibility for determining fire causerests with the Incident Commander. All fires are investigated.
Investigations are initiated to determine the cause of a fire The cause of a firemust be accurately determined before any preventative or corrective action maybe taken. If the cause is other than incendiary, preventive action may includebetter code enforcement, code modification or revision, product deficiencyrecognition and public safety education. Should the cause of a fire bedetermined as incendiary, a separate course of action would call for criminalprosecution or other legal recourse.
Frequently, fire cause determination by the field is preliminary to a more detailedexamination by Arson Section Investigators. Without proper training, the firstline fire scene investigator cannot make the decisions necessary to establish theproper fire cause.
The primary purpose of cause investigation is to determine how and why the firestarted; and for criminal fires, to establish the "Corpus Delicti” (body of the crimeor the fact a crime has occurred).
There is a natural tendency for everyone to be overwhelmed with the magnitudeand violence of the fire itself and the degree of destruction. Cause, not extent,should be the fire scene investigator's concern. Too much attention to the extenttends to obscure the search for the cause. Because of these mentalpreoccupations there is a need to develop a comprehensive analytical approachto fire investigation. Members responsible for cause and origin determinationmust have a true comprehension of how fire burns and that most fires do notbehave in the same predictable manner. Fire conditions must be consideredwith fuels, physical circumstance and the environment when establishing thecause.
There is also a tendency for some fire scene investigators to have a preferencetowards certain fire causes. These persons have the belief that most fires havea single cause. For example, electrical or smoking materials. Due to this bias,they spend much of their time trying to prove the preferred cause rather thandetermining the true cause.
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In residential occupancies, indirect losses are those costs other than structure orcontent losses. These losses include locating temporary shelter, medical care,emotional care, childcare, legal fees, transportation, days away from work, extraclothing and food costs.
There are also losses of irreplaceable items such as, pictures, records, antiquesand other heirlooms. Indirect losses to a business include; income loss due todisruption of business flow, locating and moving to a suitable locationprocessing and shipping losses, loss of business records, costs of retaining andmaintaining trained employees, loss of customers, equipment replacementcosts, legal costs and obtaining new credit which may be difficult and moreexpensive.
When both residential and business suffer indirect fire losses, the wholecommunity is affected. There are burdens and losses from employee’s payroll,welfare, unemployment, loss of taxes and revenue, and other financial losses,depending on the magnitude of the fire.
In measuring and estimating the loss for the Field Incident Reports, we are onlyconcerned with direct losses.
In order to properly estimate fire loss you must classify the type of propertyusage, type of construction, fire protection devices installed, and amount andtype of contents damaged inside or adjacent to the occupancy. With all of theabove information you can then estimate the fire loss with reasonable accuracy.
The following occupancies have been broken down into those incurring firedamage on a frequent basis. The building costs are for rebuilding on asquare-foot basis and the averages are to be used from the information youhave gathered.
Estimating content damage again applies to amount, age, type and informationgathered. Electrical components, machinery and other expensive items requiregood judgement.
When estimating fire loss, take into consideration all materials damaged by fireas well as those items damaged by smoke and water. Estimate replacements ofa like kind and quality rounding off to the nearest whole dollar.
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The average cost of contents per square foot is equal to the same amount it costs to rebuildper square foot.
The following guidelines were developed to assist fire Investigators in estimating fire loss:
Average cost for rebuilding per square foot per occupancy:
Severe Damage
Apartments 50.00 to 65.00Bank 107.00 to 143.00Churches 70.00 to 75.00Convalescent hospitals 86.00 to 112.00Homes for the elderly 70.00 to 87.00High-rise 65.00 to 100.00Hospitals 100.00 to 200.00Hotel 69.00 to 84.00Large commercial complexes 50.00 to 65.00Manufacturing commercial 50.00 to 65.00Medical offices 86.00 to 114.00Mobile home, double wide 35.00 to 41.00Mobile home, single wide 33.00 to 36.00Office 50.00 to 65.00Restaurants 80.00 to 100.00Residential
Custom homes 70.00 to 80.00Tract housing 40.00 to 50.00Garage burned-out 25.00 to 35.00Attic and roof destroyed,walls structurally sound 20.00 to 25.00
Retail store 54.00 to 72.00Schools 80.00 to 100.00Service station 80.00 to 100.00Sheds 12.00 to 18.00Steel building 15.00 to 20.00Supermarkets 55.00 to 65.00Theaters and auditoriums 107.00 to 135.00
Tilt-up construction,panelized roof destroyed,walls structurally sound 15.00 to 20.00Warehouses and most ordinarycommercial, attic and roofdestroyed, walls structurallysound 25.00 to 35.00
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Moderate Damage
Minor wall and floor repair,cleanup and painting 10.00 to 15.00
Light Damage
Little damage beyond scorchingand smoke damage, primarilya cleanup and paint job 5.00 to 10.00
Contents
Common sense and statements of occupants/owners.
Observations of Fire Department personnel.
Large warehouses containing clothing, electronics, etc. use good judgment.
EXAMPLE
A structure fire occurs involving a wood framed, single family dwelling, one storywith a composition roof. The fire has gutted one room, approximate size is 10'x15'. There is no extension into the attic. Personal property in the houseincludes; one sofa, two reclining chairs, two table lamps, two end tables a RCA1911 television, nylon shag carpet and a coffee table. Moderate water damageis incurred to the hallway carpet, smoke damage to curtains and paint,approximately 1000 square feet.
STRUCTURE LOSS 10' x15'/150 sq.feet/$40 = $ 6000
MODERATE CLEAN-UP REPAIR/1000 sq. feet/$10 10000CONTENT LOSS
1 Sofa 4002 Reclining chairs 3002 Table lamps 1002 End tables 225RCA 1911 Television 250Nylon shag carpet 350Coffee table 150
TOTAL FIRE LOSS $17,775
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One of the primary groups conducting loss analysis is the insurance industry.The insurance industry is specifically concerned with arson for profit fires.However, the information obtained from fire investigations is used for:
Recognizing and describing a community fire problem.
Supporting budget requests and allocations for additional resourcesthrough good data analysis.
Improving fire prevention end fire suppression needs.
Implementing and evaluating community awareness and educationprograms.
Revising, improving and evaluating fire code requirements.
Combating the growing arson problems.
By using the information, guidelines and averages provided in this section, youcan estimate fire losses as correctly and accurately as possible.
D. Fire Report Requests
1. The F-902 (Field Incident Report) is a public document and is availableto the general public approximately five working days after the incident.
2. Persons requesting may obtain a copy of the report by coming in personto the Arson Investigation Section office or by making a written request.A written request should include the address, date/time of incident andmust include a check or money order for the fee of $5.50 payable to theCity of Los Angeles.
To expedite the request, a self-addressed, stamped envelope should beincluded and mailed to the Arson Section Office.
3. The F-260 (Fire Investigation Report) is exempt from public disclosurewhen it involves a criminal fire under the provisions of CaliforniaGovernment Code Section 6254 (f) . This Section does direct disclosureto victims, the following information:
Names/addresses of persons involved in the incident.
Names/addresses of witnesses to the incident other than confidentialinformants.
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Date, time and location of incident.
Statements of the parties involved (victims or witnesses) other thanconfidential informants.
All diagrams.
Arson reports will only be released to a qualified/affected party or toanother law enforcement/government agency with a need to know.
Release of an active arson investigation can only be authorized by thecase Investigator, Senior Investigator, Section Captains or the SectionCommander.
4. Release of miscellaneous information to the public.
Property owners or other involved with a fire incident may be giveninformation that is readily available, as follows:
Cause of fire, dollar loss and Investigators name (if assigned).
Procedures on how to obtain a fire incident report, or otherdocuments.
Statistical and other general information available with little or nowork effort.
5. Release of information to news media
Avoid releasing information to the news media whether at the scene of afire incident or over the telephone Refer the media representative toeither the Incident Commander, the Public Information Officer(extension 5-6054) or the Community Liaison Officer (extension 5-5954).
E. Subpoena Service
1. As previously stated, the Arson Investigation Section also functions asthe Custodian of Records and as such, accepts subpoenas andsummons for members of the Fire Department. The criteria foracceptance of subpoenas is as follows:
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a. Criminal
(1) All criminal subpoenas are accepted at the ArsonInvestigation Section counter for members of the FireDepartment. There is no fee required for criminal cases.
(2) Normally, a five-day advance notice is required for themembers to appear. If there is not sufficient time,subpoenas are accepted with a waiver that there is noguarantee of the member's appearance.
b. civil
(1) Civil subpoenas are also accepted at the ArsonInvestigation Section counter. Fees must be paid at thetime of service. A payment of $150 is required for swornpersonnel.
(2) Subpoenas presented with less than five days notice, willnot be accepted.
c. Fire Department Records
(1) Subpoenas for Fire Suppression records/reports areaccepted at the Arson Investigation Section.
(2) Fire Prevention records can also be subpoenaed from theArson Investigation Section.
(3) Requests for OCD dispatch tapes and member interviewscan be made through the Arson Investigation Section.
d. Summons Acceptance
Summons for all Fire Department members can be accepted atthe Arson Investigation Section, for incidents having occurred onduty. They may also be served personally to the member at theirassignment. After proper notifications are made, the ArsonInvestigation Section prepares a letter requesting representationfrom the City Attorney's office to be signed by the Chief Engineer.
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F. 902 Operation
1. As previously noted, the 902 system serves as an automatedcode-a-phone system when certain criteria are met. To generate an"arson screen" in the 902 system, the following factors must be includedin the report:
a. Incendiary cause for the fire.
b. Suspicious cause for the fire.
c. Estimated dollar loss in excess of $24,999.
d. Juveniles playing with matches.
e. Explosion/attempt arson incidents.
f. Fatalities or serious injuries.
g. Fire Prevention Bureau occupancy.
The information received from the field will be used as criteria fordetermining the follow-up investigation, if any, needed to complete thecase. Fire Department statistics will also be taken from this informationrelative to budget, staffing and other functions.
2. Automated Code-a-Phone Procedures
These procedures should be used for all stations utilizing their data entryterminal.
a. Fire incidents:
For fire incidents, complete the routine 902 screens on yourterminal. If data entered indicates certain arson criteria, an ArsonData Screen will automatically be displayed. Complete the screenas follows:
Visually check the property and content loss boxes and, ifcorrect, enter a "Yes" in Total Checked box. If totals are notcorrect, do not complete this screen but return to the previous902 screen and correct the dollar amounts. Upon striking theEnter key, the Arson Data Screen will be returned for completion.
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This "Yes" entry is a double check indicating the correct amountshave been entered for Property and content loss for a single fireincident without exposures or that the amounts CURRENTLYDISPLAYED reflects the correct totals for the primary fire PLUSall exposures ENTERED UP TO THIS TIME.
Totals are needed as the Arson Information System uses a singlerecord for each fire incident regardless of the number ofexposures. The computer automatically adds exposure loss tothe total boxes as the exposures are entered into the 902 system,if the primary fire incident triggered the Arson Data Screen.
Enter the reason for the Code-a-Phone. The automatic triggers(reason) for the Arson Data Screen will be shown at the bottom ofthe screen and the most appropriate one shown may be used forthe Reason box.
Comments are extremely important and are requested by theArson Investigation Section. Comments are needed to explainwhat was found at the scene and anything that may be of interestto the Arson Investigation Section. The comments given areconfidential to the Arson Section and may include informationthat is of a sensitive nature.
Comments should include the following:
Whether an A-Unit was notified, but did not respond to thescene.
Name, address, phone number, and/or description, andthe connection of witnesses, suspects, arrestees, orothers involved in the incident.
Name, sex ethnic origin, date of birth, address and phonenumber of parent (s) of any involved juveniles. Also giveattitude of the juveniles and parents and the action taken,such as "counseled and released" or action recommendedby the Incident Commander.
Indicate if an A-Unit was on scene by placing an "X" in the A-Uniton scene box. The absence of an "X" will indicate the A-Unit wasNOT on scene.
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Enter the number, if any, of juveniles counseled and released inthe Juvenile C and R box.
NOTE: Report non-fire incidents (other than incendiary attempts) such asharassments or other matters of interest to the Arson Section byregular telephonic code-a-phone.
b. Bomb, Firebomb or Incendiary Device:
Description of device
Location where device was found
Who found the device.
c. Attempt Incendiary Incidents:
To code-a-phone an attempted incendiary fire using the stationcomputer terminal, complete your normal 902 screen first withcode "48" entered for Incident Type. Upon striking the Enterkey, you will receive the Arson screen.
On the Arson screen, enter "X" at A-Unit On Scene, if an A-Unitwas on scene, the number of juveniles counseled, if any,"attempt" for Reason and a brief description of attempt. Includethe type of property involved and material/ignition factor.
d. Arson Information System
Upon entry of the electronic code-a-phones, the combined data issent to a transaction file. This F-902 data is held pending theprinting out of the Arson Section daily Captain's Log. TheCaptain's Log is a combination of the previous day's incidentswhich were received via the station computer terminals.
After the Captain's Log is printed, the Arson Section FireInvestigation Reports are also printed out. These reports andtheir comments (from the Arson Screen) become the basis forfollow-up investigation by Arson Section Investigators. Thesereports are cross-referenced against the existing data base in theArson Information System. This is done to ascertain if there hasbeen any previous fire activity at the listed address or with any ofthe persons involved.
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The cases to be investigated are then assigned from thecomments that have been provided by the field. It is importantthat the names, addresses, dates of birth, descriptions, phonenumbers, license numbers and any other information the IncidentCommander feels is important, be included in the.. Commentssection.
The detection, apprehension and prosecution of persons whohave violated any of the arson laws depends on good causedetermination, preserving evidence, accurate and prompt reports,knowing when to request or telephonically contact and A-Unit,and obtaining complete information.
G. Fire Incident Report Requests
The Arson Investigation Section serves as the Custodian of Records for the FireDepartment for purposes of handling public requests for Fire Departmentrecords and has the responsibility to make certain records available to thepublic. Among these records is the Field Incident Report. This document isgenerated through the 902 system for every incident a fire company respondsto.
The Officer in Charge of that company is responsible for completing the reportin a timely manner and making it available for those persons involved in anincident. These reports can be issued to involved parties in the incident or theirrepresentatives upon payment of an established fee.
The F-902 is routinely available five working days after the incident, assuming ithas been entered into the computer. Requests for this document can be madeeither in person or by mail.
Persons wishing to only view public records can do so during normal businesshours unless these records are exempted from disclosure.
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IX. COURTROOM TESTIMONY
A. Subpoenas
The Subpoena process is the method by which the attendance of a witnessbefore a court or magistrate is required. It may be issued by any of thefollowing:
A magistrate or their clerk;
The district attorney or their Investigator;
The public defender or their Investigator.
1. Criminal on-call subpoenas
Once subpoenaed, it is the member's responsibility to contact theWitness Coordinator (telephone number will be on subpoena) and givethem the telephone number where you can be contacted on the day ofthe trial or hearing. The date on the subpoena is usually the first day ofthe ten day period in which the trial should begin. Contact the WitnessCoordinator each day and inform them of your availability for each day.They will let you know if you will be needed that day. If you anticipate notbeing available for a particular day, let the Witness Coordinator know atleast 24 hours in advance.
Contact the Subpoena Control Coordinator to confirm that you havereceived your subpoena by using voice mail at (213) 485-6341. Contactthe Arson Investigation Section to determine which Investigator ishandling the case. Contact the Investigator to discuss the case and howlong you may be needed. Let the Investigator know at that time of anyproblems you anticipate regarding your appearance or in testifying.
2. Criminal in-court subpoenas
Contact the Arson Investigation Section to determine which Investigatoris handling the case. Contact the specific Investigator to discuss thecase and what you will be testifying to. Set up a time to meet with theInvestigator and Deputy District Attorney handling the case. This isusually done on the day of the hearing or trial and you will be able toreview the records and reports prior to testifying. Let the Investigatorknow of any problems you anticipate in regards to being in court ortestifying. Review the station journal entries prior to coming to court andany notes you may have made regarding the fire.
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3. Civil court/civil deposition subpoenas
Civil subpoenas will normally be served by a process server representingthe respective law firm. Due to the fact the majority of civil cases relateback to incidents happening a number of years prior, Members shouldfamiliarize themselves with the particulars of the case.
Subpoenas for civil depositions will normally require that the memberreport to the address of the law firm indicated on the face of thesubpoena to give testimony.
Contact the Subpoena Control Officer to confirm receipt of yoursubpoena by voice mail at (213) 485-6341. Contact the ArsonInvestigation Section to determine which Investigator is handling thecase. Determine from the Investigator what you will be testifying to soyou can be prepared for court/ deposition. Review journal entries, whenpossible, and notes you may have made regarding the fire incident. Pastjournals may be requested through the Arson Investigation Section.
Due to the large case loads of many civil courts, Members should checkwith the law firm issuing the subpoena to see if they can be placed "oncall" or should attend at the time and date indicated on the subpoena.
B. Preparing for court/deposition appearance
When representing the City of Los Angeles, wear the dress uniform. Arrive ontime and when possible, arrive early. When arriving in criminal court, check inwith the court bailiff or court clerk. Contact the Deputy District Attorney handlingthe case, (bailiff will tell you who it is) and tell them you are present in Court.
Review all reports, records, evidence, and diagrams and go over possibletestimony with the Deputy District Attorney. Be familiar with dates, times,addresses, and other pertinent facts of the case.
When arriving in civil court, check in with the attorney who issued the subpoena.When discussing facts of the case with a private attorney, only discuss facts. Donot venture any guesses or opinions unless you will be testifying as an expertwitness. Remember anything you discuss can, and probably will, be brought outin open court.
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A civil deposition is usually held in a law firm office. Prior to your appearance,contact the law firm by phone to confirm your receiving the subpoena. Let thereceptionist know who you are and what you are there for. Depositions areusually more informal than a courtroom trial but most guidelines for rules of lawwill be followed. The most obvious exception is since there is no judge to' ruleon objections made by either attorney, you must answer all questions, evenafter an objection has been raised.
Don't bring anything to a deposition that hasn't been specifically subpoenaed orrequested. Be wary of discussing anything with private attorneys "off therecord". When the deposition is complete, leave the office without discussionwith either attorney.
C. Testifying
Make a good impression. Look sharp! When called to the stand, walkpurposefully and affirm the oath with a firm "I do". Look confident and credible,but not cocky. Maintain a good attitude.
You are a neutral party in this case. Only state what you observed and whenanswering questions asked from either attorney, speak with the same demeanorand tone of voice. Present a fair and impartial attitude. Always testify in a clear,firm voice. Avoid using slang, professional jargon, or profanity (unless quotingwhat someone else has said).
Be courteous to all in the courtroom. Address the judge as "your honor". Makeevery attempt to display fairness towards the defendant in criminal cases. Donot throw accusing glances or otherwise show prejudgment in manner orspeech towards the defendant.
Always refer to the defendant as the defendant. Do not use the defendantsname unless it must be included in an answer.
Always stay calm. It is a well known ploy for attorneys to try to anger you. Youshould give calm, respectful answers even though the attorney is trying to upsetyou.
When an objection is raised by either attorney, remain silent until the objectionis ruled on by the court (judge). "Objection sustained" means you cannot answerthe question. You should say nothing until asked another question. "Objectionoverruled" means you may go ahead and answer the question asked prior to theobjection if you understand the question. If you don't understand the question,state you do not understand the question. If the objection is argued for a lengthyperiod of time and you don't remember the question, ask that the question berepeated.
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Most questions can be answered with a "yes" or "no". If a more detailed answeris necessary to explain a question asked, go ahead and do it. Remember not tostray away from the original question asked. DON'T VOLUNTEERINFORMATION.
If you don't know the answer to a question, say', "I don't know". If you don'tremember a specific incident or time, say "I don't recall" or "I don't remember". Ifyou didn't hear or don't understand a question, ask that the question berepeated. Don't guess at an answer. Don't give opinions unless you have beenqualified as an expert witness. Do give honest, impartial, and complete answersto all questions asked.
During morning or afternoon breaks and lunch recess do not speak withmembers of the jury or defense attorneys. Only speak with the Deputy DistrictAttorney.
D. Testifying as an expert witness
In some criminal cases, you may be called upon to testify as an expert witnessand the defense attorney may cross examine you on your qualifications andprofessional experience. They might also take you on "voir dire". This is aFrench term meaning "to speak the truth". It is here the defense attorney will askquestions relating to your expert qualifications and experience. When statingyour qualifications, don't exaggerate nor downplay your experience and/ortraining. Remember, it is the courts final decision on whether you are qualifiedas an expert witness and able to give expert witness testimony and opinions.
In court/civil depositions, you may also be required to testify as an expertwitness. You will be asked to give your qualifications and experience just as youwould if you were in court.
Anyone with special knowledge or experience with respect to the subject inquestion (fire cause determination) may qualify through a showing of training orexperience to testify as an expert. The final decision as to who may testify as anexpert rests with the court.
In nearly all criminal cases, you will be testifying as a witness for theprosecution. You may be asked to give testimony as to the incendiary nature ofthe fire and how it relates to a particular case. It is important you meet prior tocourt with the Deputy District Attorney handling the case to determine what youwill be expected to testify to. Go over your qualifications and professionalexperience that may qualify you as an expert witness.
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Be familiar with the questions ahead of time that the Deputy District Attorney willask in qualifying you as an expert witness. These questions will usually relate toyour formal as well as on the job training.
A sample questionnaire containing questions which may arise during testimonyto qualify you as an expert are as follows:
Who are you employed by?
How long have you been a member of the Fire Department?
What is your present assignment?
How long have you been in your present assignment?
What are your duties and responsibilities in your present assignment?
Have you attended any courses or received any special training in firecause and origin determination?
How many fires have you investigated to determine the cause andorigin?
Have you qualified in court as an expert witness?
On (date), what was your assignment?
Did you respond to an incident at (location)?
What were your observations when you arrived at the scene?
Did you conduct an investigation to determine the cause and origin forthe fire?
Did you form an opinion as to the cause of the fire?
What is your opinion as to the cause and origin of this fire?
The answer should be limited to a statement of the most probablesource of ignition and the first material ignited.
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What did you base your opinion on?
This question should be answered based on the physical evidenceobserved at the scene.
Be prepared to explain exactly what information you based your opinionon and how the evidence and/or statements played a role in thedevelopment of your opinion.
Remember, almost anything is possible. You will, in all probability, be given ahypothetical set of facts slightly different than the facts you based your opinionon. You may then be requested to give an opinion based on this hypotheticalset of facts. Don't be afraid to modify your opinion. You can add your commentsas to why the hypothetical set of facts is different or not applicable to thisparticular case. As an expert witness you may also offer information to explainor clarify your answers to preclude the possibility of misleading the court. This isextremely important. When you are testifying as an expert, you are allowed thislatitude to explain your opinions as long as it is pertinent to the formulation ofyour answer. This latitude is not allowed when responding as a lay witness toquestions not involving expert opinion.
E. Definitions
1. Juvenile hearing
Although less formal than an adult trial, the rules and procedures of thecourt still are to be followed. There is no jury and the judge or juvenilecommissioner rules on the outcome of the trial. You will still be called tothe witness stand and will testify under oath.
2. City Attorney trial/hearings
This is a trial or hearing where misdemeanor cases are handled. Mostarson cases are felonies, but some may be reduced to misdemeanorsand you can be called to testify in those incidents. Remember themisdemeanor cases are also handled in a courtroom and your conductshould be the same as in any other courtroom.
3. Preliminary hearing
This usually occurs within ten days of the arraignment which must occurwithin 48 hours of the arrest excluding holidays and week-ends. Theexception to this is when the defendant bails out or waives time.
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The purpose of this hearing which is before a judge (no jury) is for thepeople (prosecution) to establish a "prima facie" case (Latin termmeaning "first appearance") to show there is sufficient evidence to showa crime has occurred and there is probable cause to show the defendantis responsible for that crime.
4. Superior Court trial
This trial is held within 60 days of the Superior Court arraignment. Thepurpose of this trial is to establish the innocence or the guilt (beyond areasonable doubt) of the defendant. It is the defendants choice to have atrial by jury (twelve men or women) or by the court (judge only).
5. Civil Court trials
A non-criminal trial where one individual/company (plaintiff) is suinganother individual/company (defendant). These trials usually involveproduct liability, negligence, or bad faith suits against insurancecompanies.
6. Civil depositions
These informal meetings usually involve two or more attorneysrepresenting plaintiffs and defendants involved in civil litigation. Both theplaintiffs attorney and the defendants attorney will question you. There isa court reporter present to take down all questions and answers. Civildepositions are usually conducted prior to going to civil trial.
7. Voir Dire
A procedure in which questions are asked by an attorney or the court totest the witnesses competency and expertise relating to elements orissues pertaining to a particular subject or case. This is usuallyapplicable in our situation to qualifying as an expert witness. The courthas the final decision as to whether a witness can testify as an expert.
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X. ARSON LAWS
A. California State Penal Code
1. Section 450- Definitions:
a. Structure - any building, or commercial or public tent, bridge,tunnel or powerplant.
b. Forest land - any brush covered land, cut-over land, forest,grasslands, or woods.
c. Property - real property or personal property, other than astructure or forest land.
d. Inhabited - currently being used for dwelling purposes whetheroccupied or not. "Inhabited structure" and "inhabited property" donot include the real property on which an inhabited structure oran inhabited property is located.
e. Maliciously - imports a wish to vex, defraud, annoy or injureanother person, or an intent to do a wrongful act, establishedeither by proof or presumption of law.
f. Recklessly - a person is aware of and consciously disregards asubstantial and unjustifiable risk that his or her act will set fire to,burn, or cause to burn a structure, forest land, or property. Therisk shall be of such nature and degree that disregard thereofconstitutes a gross deviation from the standard of conduct that areasonable person would observe in the situation. A person whocreates such a risk but is unaware thereof by reason of voluntaryintoxication also acts recklessly with respect thereto.
2. Section 451 - Punishment for Arson.
A person is guilty of arson when he or she willfully and maliciously setsfire to or burns or causes to be burned or who aids, counsels or procuresthe burning of, any structure, forest land or property.
a. Arson that causes great bodily injury is a felony punishable byimprisonment in the state prison for five, seven, or nine years.
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b. Arson that causes an inhabited structure or inhabited property toburn is a felony punishable by imprisonment in the state prisonfor three, five, or eight years.
c. Arson of a structure or forest land is a felony punishable byimprisonment in the state prison for two, four, or six years.
d. Arson of property is a felony punishable by imprisonment in thestate prison for 16 months, two, or three years. For purposes ofthis paragraph, arson of property does not include one burning orcausing to be burned his or her own personal property unlessthere is an intent to defraud or there is injury to another person oranother person's structure, forest land or property.
3. Section 452 - Punishment for unlawfully causing a fire.
A person is guilty of unlawfully causing a fire when he or she recklesslysets fire to or burns or causes to be burned, any structure, forest land orproperty.
a. Unlawfully, causing a fire that causes great bodily injury is afelony punishable by imprisonment in the state prison for two,four, or six years, or by imprisonment in the county jail for notmore than one year, or by a fine, or by both such imprisonmentand fine.
b. Unlawfully causing a fire that causes an inhabited structure orinhabited property to burn is a felony punishable by imprisonmentin the state prison for two, three, or four years, or byimprisonment in the county jail for not more than one year, or bya fine, or by both such imprisonment and fine.
c. Unlawfully causing a fire of a structure or forest land is a felonypunishable by imprisonment in the state prison for 16 months,two, or three years, or by imprisonment in the county jail for notmore than six months, or by a fine, or by both such imprisonmentand fine.
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d. Unlawfully causing a fire of property is a misdemeanor. Forpurposes of this paragraph, unlawfully causing a fire of propertydoes not include one burning or causing to be burned his/her ownpersonal property unless there is injury to another person or toanother person's structure, forestland or property.
e. In the case of any person convicted of violating this section whileconfined in a state prison, prison camp, prison forest camp orother prison camp or prison farm, or while confined in a countyjail while serving a term of imprisonment for a felony ormisdemeanor conviction, any sentence imposed shall beconsecutive to the sentence for which the person was thenconfined.
4. Section 453 - Possession of flammable or explosive materials;Manufacture of firebombs.
a. Every person who possesses any flammable, explosive orcombustible material or substance, or any device in anarrangement or preparation, with intent to willfully and maliciouslyuse such material, substance or device to set fire to or burn anystructure, forest land, or property, is punishable by imprisonmentin the county jail, not exceeding one year.
b. Every person who possesses, manufactures, or disposes of afirebomb is guilty of a felony (For purposes of this section,"disposes of" means give, give away, loan, offer, offer for sale,sell, or transfer). A "firebomb" is a breakable container containinga flammable liquid with a flash point of 150 degrees Fahrenheit orless, having a wick or similar device capable of being ignited.
5. Section 455 - Attempts; commission of preliminary acts.
Any person who willfully and maliciously attempts to set fire to orattempts to burn or to aid, counsel or procure the burning of anystructure, forest land or property or who commits any act preliminarythereto, or in furtherance thereof, is punishable by imprisonment in thestate prison for 16 months, two, or three years.
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The placing or distributing of any flammable, explosive or combustiblematerial or substance, or any device in or about any structure, forestland or property in an arrangement or preparation with intent toeventually willfully and maliciously set fire to or burn same, or to procurethe setting fire to or burning of the same shall, for the purposes of thisact constitute an attempt to burn such structure, forest land or property.
6. Section 456 - Fine imposed on conviction for felony.
a. Upon conviction for any felony violation of this chapter, inaddition to the penalty prescribed, the court may impose a finenot to exceed fifty thousand dollars ($50,000) unless a greateramount is provided by law.
b. When any person is convicted of a violation of any provision ofthis chapter and the reason he committed the violation was forpecuniary gain, in addition to the penalty prescribed and insteadof the fine provided in subdivision a, the court may impose a fineof twice the anticipated or actual gross gain.
7. Section 12303.3 - Possession, explosion, or igniting of a destructivedevice with intent to injure or intimidate.
Every person who possesses, explodes, ignites or attempts to explodeor ignite any destructive device or any explosive with intent to injure,intimidate or terrify any person, or with intent to wrongfully injure ordestroy any property, is guilty of a felony, and shall be punished byimprisonment in the state prison for a period of three, five, or sevenyears.
8. Section 148.2 - Interfering with firefighter or emergency rescuepersonnel at fire.
Every person who willfully commits any of the following acts at theburning of a building or at any other time and place where any firefighteror firefighters or emergency rescue personnel are discharging orattempting to discharge an official duty is guilty of a misdemeanor:
a. Resists or interferes with the lawful efforts of any firefighters oremergency rescue personnel in the discharge or attempt todischarge an official duty.
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b. Disobeys the lawful orders of any firefighter or public officer.
c. Engages in any disorderly conduct which delays or prevents a firefrom being timely extinguished.
d. Forbids or prevents others from assisting' in extinguishing a fireor exhorts another person, as to whom he has no legal right orobligation to protect or control, from assisting in extinguishing afire.
9. Section 148.3 - False report of emergency.
a. Any individual who reports, or causes any report to be made, toany city, county, city and county, or state department, district,agency, division, commission, or board, that an "emergency"exists, knowing that such report is false, is guilty of amisdemeanor and, upon conviction thereof, shall be punishableby imprisonment in the county jail, not exceeding one year, or bya fine, not exceeding one thousand dollars ($1,000), or by bothsuch fine and imprisonment.
b. Any individual who reports, or causes any report to be made, toany city, county, city and county, or state department, district,agency, division, commission, or board, that an "emergency"exists, knowing that such report is false, and great bodily injury ordeath is sustained by any person as a result of such false report,is guilty of a felony and upon conviction thereof shall bepunishable by imprisonment in the state prison, or by a fine of notmore than ten thousand dollars ($10,000), or by both such fineand imprisonment.
c. "Emergency" as used in this section means any condition whichresults in, or which could result in, the response of a public officialin an authorized emergency vehicle, or any condition whichjeopardizes or could jeopardize public safety and results in, orcould result in, the evacuation of any area, building, structure,vehicle or of any other place which any individual may enter.
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10. Section 148.3 - Tampering with fire protection equipment;
a. Any person who willfully and maliciously tampers with, molests,injures, or breaks any fire protection equipment, fire protectioninstallation, fire alarm apparatus, wire or signal, or willfully andmaliciously sends, gives, transmits, or sounds any false alarm offire, by means of any fire alarm system or signal or by any othermeans or methods,' is guilty of a misdemeanor and uponconviction thereof shall be punishable by imprisonment in thecounty jail, not exceeding one year, or by a fine, not exceedingone thousand dollars ($1000), or by both such fine andimprisonment.
b. Any person who willfully and maliciously sends, gives, transmits,or sounds any false alarm of fire, by means of any fire alarmsystem or signal, or by any other means or methods, and greatbodily injury or death is sustained by any person as a resultthereof, is guilty of a felony and upon conviction thereof shall bepunishable by imprisonment in the state prison or by a fine of notless than five hundred dollars ($500) nor more than ten thousanddollars ($10,000), or by both such fine and imprisonment.
B. California State Insurance Code
1. Section 1871.1 - False or fraudulent claim.
It is unlawful to:
a. Present or cause to be presented any false or fraudulent claimfor the payment of a loss under a contract of insurance.
b. Prepare, make, or subscribe any writing, with intent to present oruse the same, or to allow it to be presented or used in support ofany claim.
Every person who violates any provision of this section is punishable byimprisonment in the state prison for two, three, or five years, or by finenot exceeding fifty thousand dollars ($50,000), or by both unless thevalue of the fraud exceeds fifty thousand dollars ($50,000), in whichevent the fine may exceed the value of the fraud.
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C. Los Angeles Municipal Code
1. Fireworks
Section 57.55.01.
a. It shall be unlawful for any person to use give, possess, sell ordischarge any fireworks, except that under permit by the chiefand in accordance with the provisions of the Health and SafetyCode of the State of California, patriotic, civic, and religiousorganizations may conduct public fireworks displays. Everydisplay shall be under the control and supervision of aPyrotechnic Operator, licensed by the State Fire Marshal andshall be conducted under conditions as required by the Chief.The fireworks in public displays shall be located, discharged, andof such character so as not to be hazardous to persons orproperty.
b. Fireworks may be shipped, delivered or sold for delivery, to pointsoutside this City where the sale or use thereof is lawful, by anywholesaler, retailer, jobber, warehousemen, or a manufacturer, ormanufactured for such sale or distribution only, or kept in storagein a safe and secure place pending the lawful removal thereof;but no fireworks shall be handled, manufactured or storedhereunder without the express written approval of the Chief. Suchapproval shall be revocable for cause and shall be granted onlyupon application therefor, setting forth a description of the placeof storage or manufacture and such other information as theChief shall require.
c. Storage: Fireworks shall be stored in compliance with thefollowing:
(1) A maximum of 500 pounds may be stored in approvedportable magazines complying with the provisions ofL.A.F.D. Standard No. 40 and in a location approved bythe Chief.
(2) Quantities in excess of 500 pounds shall be stored in aroom of one-hour, fire-resistive construction. Dooropenings therein shall be protected by one-hourassemblies. Such rooms shall. be equipped with anautomatic sprinkler system.
d. Violations and filings related to fireworks will be handled by theLAFD Legal Unit.
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XI. GLOSSARY
ACCELERANTSomething, usually a flammable liquid, used to increase the spread of fire.
ACCIDENTALA fire caused by chance, by natural causes, by design or mechanicalfailure/malfunction. The nonintentional act (or failure to act) of a human being.
ALLIGATORINGChar patterns formed on burned wood.
AMPERE (AMP)A unit of flow of electricity.
ANNEALINGTo heat metal or glass, and then slowly cool resulting in a less brittle (softer)material.
ARCWhen an electric current is interrupted, either intentionally (by a switch) oraccidentally (because of a loosened terminal), heating that results from highresistance.
AREA OF ORIGINThe general area where a fire may have started. It is not limited to the specificpoint of origin.
ARSONA crime. The willful and malicious burning of a structure, forestland or property.
ARSONISTAny person who willfully and maliciously sets fires.
AUTOPSYInspection and partial dissection of a dead body to determine the cause ofdeath.
BACKDRAFTAn explosion or rapid burning of heated gases resulting from the introduction ofoxygen when air is admitted to a building heavily charged by smoke from a firewhich has depleted the oxygen of a building.
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BOILOVEROverflow of flammable liquid from a container due to heat from a fire, or due tothe excessive application of water which agitates and floats the burning liquidover the top of the container.
BREACHOpening made in a wall to permit rescue, operation of hose lines or removal ofstock.
BRITISH THERMAL UNITThe amount of heat necessary to raise the 'temperature of one pound of waterone degree Fahrenheit.
BURGLARYThe entering of any structure with the intent to commit grand or petty larceny orany felony.
BURN PATTERNUsed to define and illustrate the progress of a fire by means of visible charring,decomposition, and displacement.
CALCINATIONThe dehydration of wallboard (gypsum) when exposed to heat.
CARBON MONOXIDEOne of the most common gases found in structural fires and is highlyflammable.
CAUSEUsed to identify and describe the igniting agent or heat source of a particularfire.
CHAIN OF EVIDENCEThe chain of custody (possession) of an item of evidence from the point in timewhere it was first discovered until the time that it is offered as an exhibit in court.
CHARThe remains of burned materials.
CHECKERINGThe breaking of heated glass when water is applied to its surface.
CIRCUIT BREAKERA type of electrical overcurrent device.
CIVIL DISORDERSAlso riots and/or political activity. Fire is used as a weapon often creating theillusion a large group of people is involved in firesetting in a specific area. (SeeMotives)
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CLASS A FIRESFires involving ordinary combustibles best extinguished by cooling action.
CLASS B FIRESFires involving flammable liquids usually extinguished by smothering agents.
CLASS C FIRESFires involving equipment live electrical
CLASS D FIRESFires involving combustible metals.
COMBUSTIBLEA material that will ignite and burn when sufficient heat is applied.
COMBUSTIBLE LIQUIDA liquid having a flash point at or above 100 degrees F.
CONDUCTIONThe process by which heat is communicated from one body to another by directcontact or through an intervening solid, liquid, or heat-conducting medium.
CONFLAGRATIONA major fire usually covering a considerable area and one which crosses naturalfire barriers usually involving buildings in more than one block and frequentlyresulting in a large loss.
CONVECTIONThe transfer of heat by a circulating medium, usually a gas or a liquid.
CORPUS DELECTIThe fundamental facts (elements) necessary to prove the commission of a crime(body of the crime).
CRAZINGStress cracks in glass as a result of heating.
CRIME COVERA fire set to cover another crime. It is assumed the fire will destroy evidence ofthe original crime. (See Motives)
CURRENT ELECTRICITYEnergy that is transferred through conductors by means of the movement offree electrons that migrate from atom to atom inside the conductor.
DEAD LOADThe weight of the structure and any equipment and appliances permanentlyattached.
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DEBRISThe results of f ire destruction; rubble at a fire scene.
DEEP-SEATEDA fire that has burrowed into baled stocks, grain storage and other combustiblesas contrasted with a surface fire. Deep charring of structural members.
DEVICEAny mechanical means used to start a fire or explosion.
DIVISION WALLA wall which effectively divides a building into separate fire areas. Also knownas a fire wall.
EVIDENCEThat which makes clear or ascertains the truth of the very fact or point in issue,whether from the prosecution or the defense.
EXPLOSIONThe sudden and rapid escape of gases from a confined space, accompanied byhigh temperatures, violent shock, and a loud noise.
Mechanical- an explosion that occurs within a container or vessel.
Chemicals an explosion caused by the rapid conversion of a chemicalcompound into gases.
Nuclear- an explosion occurring within the atom of an element and may beeither nuclear fission or nuclear fusion.
EXPLOSIVE LIMITSThe upper and lower percentage of air/gas mixture in which combustion will besupported. (Flammable limits)
EXPOSUREProperty that may be endangered by a fire in another structure or by an outsidefire.
FIRERapid oxidation usually with the evolution of heat and light.
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FIRE BEHAVIORThe manner in which fuel ignites, flame develops and fire spreads. Sometimesused with reference to the characteristics of a particular fire as distinguishedfrom normal fire characteristics.
FIRE LOADThe measure of the maximum heat that would be released if all thecombustibles in a given fire area burned.
FIRE RESISTIVEA structure or assembly of materials built to provide a predetermined degree offire resistance usually as called for by building and fire prevention codes.
FIRE STOPPINGThe blocking off of concealed spaces of structures to prevent unseen extensionof fire throughout walls and ceilings.
FIRE TETRAHEDRONFlame usually has four parts which are necessary for self-sustaining openflaming combustion. They are heat, fuel, oxygen and an uninhibited chainreaction among all parts of the tetrahedron.
FIRE TRIANGLEThe components, heat, fuel and oxygen, that when joined together, generatefire.
FLAMEThe light given off by burning gases.
FLAME RESISTANTMaterial or surface of a nature that does not propagate flame once an outsidesource of flame has been removed.
FLAME SPREADThe rate at which flames spread over surfaces of various materials such asbuilding finishes, fabrics, etc.
FLAMMABILITYThe relative ease with which various fuels ignite and burn, regardless of thequantity of fuel involved.
FLAMMABLEA combustible material that ignites easily, burns intensely, or has a rapid rate offlame spread. (Same as inflammable)
FLAMMABLE LIQUIDA liquid having a flash point below 100 degrees F.
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FLASHBACKTendency -of a flammable liquid fire to flash from the source of ignition back tothe flammable liquids container.
FLASHOVERStage of fire when a room or other area becomes heated to the point whereflames flash over the entire surface or area.
FLASH POINTThe lowest temperature at which a substance gives off vapor sufficient to forman ignitable mixture with the air near the surface of the substance.
FORCIBLE ENTRYTechniques used by fire departments to enter closed and locked buildings withminimum delay and property damage.
FRAUDA deception deliberately practiced in order to secure unfair or unlawful gain.(See Motives)
FREE-BURNING PHASEA phase where the fire is fully developed after drawing in air from thesurrounding atmosphere. Oxygen content of area is usually reduced to 16% to18%.
FUSEEA common road flare.
GHOST MARKSCaused by the application of a flammable liquid to a surface that is covered withasphalt tile.
GROUND FAULTAn insulation failure between a conductor and ground, where the failure is not toa grounded conductor normally intended to carry current in the circuit.
HEATTemperatures above the normal atmospheric temperatures, as produced by theburning or oxidation process.
HEAT FRACTURINGGlass that breaks due to a slow buildup of heat. Generally smaller than crazing.
HEAT TRANSFERThe transfer of heat by convection, conduction, and/or radiation.
HOMICIDE (murder)The unlawful killing of a human being, or a fetus, with malice aforethought.(Murder)
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HUMIDITYA moderate degree of dampness in the atmosphere.
IGNITIONThe beginning of flame propagation or burning. The starting of a fire.
IGNITION TEMPERATUREThe minimum temperature to which a substance must be heated in air in orderto ignite independently of the heating element.
IMPACT LOADLoads which are delivered in a short period of time. Examples of impact loadsare explosions, winds and earthquakes.
INCENDIARYA fire set by a human being with willful and malicious intent.
INCENDIARY DEVICEA device which would assist in the setting and/or spreading of a fire. It may alsooffer a delay factor.
INCIPIENT PHASEFirst stage of fire development after ignition. Flames are localized and room hasa normal oxygen content and temperature.
INTENTThe deliberateness of the act.
INVERTED "V" PATTERNA burn pattern created by very rapid intense combustion. The highly heatedgases rise vertically and the thermal column draws the adjacent air in towardsthe flame in a venturi type action. The pattern exhibited is a shape similar to amountain peak with a sharp line of demarcation between severe and moderatechar or heat. Indicates the possible presence of a flammable accelerant.
JUVENILESThose under the age of 18. Although not a motive, this age group is ofteninvolved in many different types of firesetting. (See Motives)
KNOCKDOWNTo reduce flame and heat so as to prevent danger of further extension of fire.
LIGHTNINGThe discharge of electrical energy from a cloud to an opposite charge onanother cloud or the ground.
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LIVE LOADAny load other than a dead load. Examples of common live loads areoccupants, storage and furnishings.
L. P. GASLiquefied petroleum gas. One of several petroleum products such as butane orpropane stored under pressure as a liquid and vaporized and burned as gas.
MATCHBOOK DEVICEAn incendiary device consisting of a paper matchbook with an ignited cigaretteplaced within its cover, eventually igniting the matches.
MOLOTOV COCKTAILA breakable container filled with a flammable liquid. It may be ignited either by awick or a variety of other means. (Firebomb) generally thrown.
MOTIVEA reason for things being done. Something that causes a person to act (Seespecific motives under separate headings).
NEGATIVE CORPUSThe establishment of a criminal fire based on the methodical elimination of allnatural, mechanical and accidental causes for the fire.
NONCOMBUSTIBLENot subject to combustion under ordinary conditions of temperature and normaloxygen content of atmosphere.
NONFLAMMABLEMaterial which will not burn under most conditions.
OHMSResistance. Opposition offered by a material to the flow of current.
OVERHAULA term used to cover or describe the operation of looking for a hidden flame orspark that may rekindle the fire.
POINT OF ORIGINThe precise location of initial ignition of the substance involved, usually thelocation of the heat source.
PROTECTED AREAThe clean or unburned area left by stock, furniture, contents etc., coveringshelves, floors, or other combustible fuels.
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PYRO/PSYCHOShort for pyromaniac. The uncontrollable impulse to start fires. (See Motives)
PYROLYSISThe chemical decomposition of matter through the action of heat.
PYROMANIAThe uncontrollable impulse to start fires.
PYROPHORIC CARBONPure carbon that has the ability to absorb heat and can become hot enough tocause surrounding fuels to reach ignition temperature.
PYROPHORIC MATERIALSMaterials that ignite spontaneously.
RADIATIONThe transfer of heat from one body to another by heat rays through interveningspace. Much the same manner as light is transferred by light rays.
REKINDLEThe re-ignition of a fire due to latent heat, sparks or embers, or due to thepresence of smoke or steam.
SEARCH AND SEIZUREInvolves the examination of ones house or other buildings or premises, or theirperson, with a view to the discovery of contraband or some evidence of guilt.This may be used in the prosecution of a criminal action for some crime oroffense with which one may be charged.
SEAT OF FIREArea where main body of fire is located as determined by outward movement ofheat and gases and where the fire is most deep seated.
SETIncendiary fire, or the point or points of origin of an incendiary fire.
SHORT CIRCUITA fault where there is an abnormal connection between two points of differentvoltage in a circuit.
SMOLDERING PHASEThe decaying stage of the fire where the oxygen may drop below 15%, fillingthe area with dense smoke.
SMOKE DAMAGEDamage caused by smoke when it is not accompanied by fire damage.
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SPALLCrumbling or fracturing of pieces of concrete or brick during exposure to heat ormechanical force. It may be indicative of elevated localized heating as a resultof a concentrated fuel load such as burning flammable liquid. Spalling may alsobe the result of rapid cooling of the surface or expanding moisture/steam withinthe masonry material.
SPECIFIC GRAVITYThe ratio of the weight or mass of the given volume of a substance to that of anequal volume of another substance used as a standard.
SPITE/REVENGETo set a fire in an act of retaliation in order to get even. (See Motives)
SPONTANEOUS IGNITIONThe process wherein substances or compounds ignite as a result of an increasein temperature of the substance or compound without an independent outsideignition source and without drawing heat from its surroundings.
SPOT FIRESFires started by airborne embers or burning debris from an established fire.
STATIC ELECTRICITYAn electric charge produced by an actual transfer of electrons from some atomsonto others.
SUBPOENAA writ or order requiring the attendance of a person at a particular time andplace to testify as a witness.
SUSPICIOUSWhere circumstances and logic indicate an incendiary fire, and an accidentalcause cannot be eliminated.
TORCHA professional firesetter.
TRAILERSLong trails of fast-burning materials used by arsonists to rapidly spread the firefrom one area to another.
UNDETERMINEDA fire where there is more than one viable cause, none of the possible causesindicating an incendiary fire. The specific cause or opinion as to the causecannot be established.
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UTILITIESRelating to fire investigation, the electricity, water and gas entering a structure.
“V" PATTERNA burning pattern created by the normal growth of fire in an upward and outwardmanner.
VANITYA fire set by an individual who wants attention for finding and sometimesextinguishing a fire. A fire set by someone who also seeks to secure their jobposition. (See Motives)
VAPORA substance in the gaseous state as distinguished from the liquid or solid state.
VAPOR DENSITYThe ratio of a given volume of gas to an equal volume of air.
VENTILATIONA technique for opening a burning building to remove heated gases and smoke,to prevent explosive concentrations and to permit-advancement of hose linesinto effective positions for fire extinguishment.
VOLATILITYTendency of a material to readily vaporize.
VOLTA unit of electrical pressure, the force which causes electricity to flow through aconductor.
WATTThe watt is a unit of power. A current of one ampere flowing under pressure ofone volt equals one watt.
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XII. BIBLIOGRAPHY
Books
Carter, Robert E. Arson Investigation.PUBLISHER, 1978.
Cole, Lee S. Investigation of Motor-Vehicle Fire.3rd Edition, Lee Books, 1992.
DeHaan, JohnFire Investigation.3rd Edition, PUBLISHER, DATE.
Few, Edward W. Wildland Fire Protection for the Western PacificUnited States Forest Service, 1985.
Fitch, Richard D., and Porter, Edward Accidental or Incendiary.PUBLISHER, 1974.
French, Harvey M. The Anatomy of Arson.PUBLISHER, 1979.
Kennedy, John. Fire-Arson-Explosion Investigation.Investigation Institute, 1977.
Powell, William. The Anarchist Cookbook.Barricade Books Inc., 1977.
Yereance, Robert A. Electrical Fire Analysis,Charles C. Thomas Publishing, 1987.
Reference Works
Arson Investigation and Prosecution Symposium.California District Attorneys Association, 1984.
Arson. Some Problems and Solutions. NFPA Publication#SPP.38, 1976.
California Penal Code.West Publishing, 1993.
Fire/Arson Detection - Instructors Guide. National Fire Academy,National Emergency Training Center, 1989.
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Fire/Arson Investigation. National Fire Academy,National Emergency Training Center, 1989.
Fire Cause Determination for Company Officers. National FireAcademy, United States Fire Administration, June 1993.
Fire Code City of Los Angeles, Article 7 of Chapter V of the LosAngeles Municipal Code, 1992.
Fire Investigation. California Department of Forestry,Fire Academy, DATE.
Fire Investigation Handbook. United States Department ofCommerce, 1980.
Fire Investigation 1 and 2 Instructors Manuals. California FireService Training and Education Service, 1988.
Fire Investigation 1 and 2 Student Manuals. California FireService Training and Education Service, 1988.
Fire investigation Training manual. Los Angeles Fire DepartmentArson Investigation Section, 1994.
Fire Protection Handbook. 17th Edition, NFPA, 1992.
Los Angeles Municipal Code. City of Los Angeles, DATE
Manual for Investigation of Vehicle Fires. National AutomobileTheft Bureau, 1986.
Manual of the Los Angeles Police Department City of Los Angeles, 1993.
Pocket Guide to Arson Investigation. Factory Mutual EngineeringCorporation, 4th Edition, 1992.
Bulletins
Roof and Building Construction, Los Angeles Fire Department,Training Bulletin No. 19, April 1983.
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