The Crime SceneThe Crime SceneChapter 2Chapter 2

Johnston High SchoolJohnston High School

ForensicsForensics

Learning GoalsLearning Goals

1)1) Define physical evidenceDefine physical evidence

2)2) Discuss responsibilities of first Discuss responsibilities of first officer arriving at sceneofficer arriving at scene

3)3) Explain steps to be taken to Explain steps to be taken to thoroughly record crime scenethoroughly record crime scene

4)4) Describe proper procedures for Describe proper procedures for conducting systematic search for conducting systematic search for evidenceevidence

More learning goals…More learning goals…

5) Describe proper techniques for 5) Describe proper techniques for packaging common types of physical packaging common types of physical evidenceevidence

6) Define and understand concept of 6) Define and understand concept of chain of custodychain of custody

7) Understand contributions of the 7) Understand contributions of the forensic pathologist, entomologist, forensic pathologist, entomologist, and anthropologist can make to a and anthropologist can make to a homicide investigationhomicide investigation

Physical Evidence Physical Evidence

Physical Evidence: Any object that Physical Evidence: Any object that can establish that a crime has been can establish that a crime has been committed or can link a crime to its committed or can link a crime to its victim or its perpetrator.victim or its perpetrator.

Importance of EvidenceImportance of Evidence

Forensic Science begins at the crime Forensic Science begins at the crime scene!scene!

Scientist must be able to RECOGNIZE Scientist must be able to RECOGNIZE evidenceevidence

Must be able to COLLECT evidenceMust be able to COLLECT evidence Must be able to PRESERVE evidenceMust be able to PRESERVE evidence Remember…garbage in, garbage Remember…garbage in, garbage

out!out!

Approaching a Crime SceneApproaching a Crime Scene

Securing and Isolating Securing and Isolating Crime SceneCrime Scene

The The first officerfirst officer at the scene must… at the scene must…1) offer medical assistance when 1) offer medical assistance when needed and/or make an arrestneeded and/or make an arrest2) exclude all unauthorized personnel 2) exclude all unauthorized personnel from scene (very hard!)from scene (very hard!)3) Call for assistance/backup3) Call for assistance/backup4) isolate area (tape, barricades)4) isolate area (tape, barricades)

Must try to preserve and protect area as Must try to preserve and protect area as much as possiblemuch as possible

Once Secured…Once Secured…

Lead investigator evaluates area Lead investigator evaluates area Determines boundariesDetermines boundaries Establishes perpetrator’s path Establishes perpetrator’s path

(entry and exit) (entry and exit) Obvious evidence documented Obvious evidence documented

and photographedand photographed Initial walk-through & develop Initial walk-through & develop

strategy for examination strategy for examination

Recording the SceneRecording the Scene

Limited time to work in CS in Limited time to work in CS in untouched stateuntouched state Records useful for investigation/courtRecords useful for investigation/court What are some methods of recording What are some methods of recording

the crime scene?the crime scene?

Recording the Crime Recording the Crime SceneScene

PhotograpPhotographshs

SketchesSketchesNotesNotes

PHOTOGRAPHYPHOTOGRAPHY

Take unaltered!Take unaltered! Do not move evidence until picture is Do not move evidence until picture is

taken!taken! If moved, must be recorded in notesIf moved, must be recorded in notes All photos must show position and location All photos must show position and location

to crime sceneto crime scene Close ups of smaller items must be takenClose ups of smaller items must be taken Use a ruler or scale to note sizeUse a ruler or scale to note size Videotaping???Videotaping???

PhotographyPhotographySceneScene

Multiple Multiple viewsviews

EntrancesEntrancesExitsExitsWindowsWindows

EvidenceEvidenceClose upsClose upsPerspectivPerspectivesesMultiple Multiple anglesangles

SketchesSketches

After photographing…make a After photographing…make a rough rough sketchsketch Drawn at crime sceneDrawn at crime scene Contains accurate depictions of Contains accurate depictions of

dimensions of scene (use tape dimensions of scene (use tape measurer)measurer)

Shows location of all objects having Shows location of all objects having bearing on the casebearing on the case

Finished SketchFinished Sketch

Done carefully, attention to Done carefully, attention to appearanceappearance

Must reflect rough sketch (admissible Must reflect rough sketch (admissible in court)in court)

Computer Aid Drafting (CAD) -Computer Aid Drafting (CAD) -software for reconstructing software for reconstructing

Drawn to scaleDrawn to scale

Rough Sketch to FinalRough Sketch to Final bsapp.com

Rough vs Finished SketchRough vs Finished Sketch

NotesNotes Match to sketchMatch to sketch Constant activityConstant activity Quick, short, bulletedQuick, short, bulleted What can you not see from the photo?What can you not see from the photo? Helpful for long-term cases - memoryHelpful for long-term cases - memory Identifies all evidence – what is it? Identifies all evidence – what is it?

Who collected?Who collected? Tape recording used sometimesTape recording used sometimes

What should be noted?What should be noted?

These notes must identify:These notes must identify: Time an item of physical evidence was Time an item of physical evidence was

discovereddiscovered Who discovered it?Who discovered it? How and by whom it was packaged and How and by whom it was packaged and

markedmarked Disposition of an item after it was Disposition of an item after it was

collectedcollected May be the only source of information May be the only source of information

for refreshing one’s memoryfor refreshing one’s memory

The Search – Part 1The Search – Part 1 The search for physical evidence at a crime The search for physical evidence at a crime

scene must be thorough and systematic.scene must be thorough and systematic. The search pattern selected will normally The search pattern selected will normally

depend on the size and locale of the scene depend on the size and locale of the scene and the number of collectors participating and the number of collectors participating in the search.in the search.

For a factual, unbiased reconstruction of For a factual, unbiased reconstruction of the crime, the investigator—relying upon the crime, the investigator—relying upon his or her training and experience—must his or her training and experience—must not overlook any pertinent evidence.not overlook any pertinent evidence.

Physical evidence can be anything from Physical evidence can be anything from massive objects to microscopic traces.massive objects to microscopic traces.

Search PatternsSearch Patterns

The Search – Part 2The Search – Part 2

Often, most evidence is clearly visible, Often, most evidence is clearly visible, BUT…BUT… Others can only be detected via examination in Others can only be detected via examination in

the labthe lab Must collect ALL possible carriers of trace Must collect ALL possible carriers of trace

evidenceevidence Clothing Clothing Vacuum sweepingsVacuum sweepings Rug samplesRug samples Fingernail scrapingsFingernail scrapings

Beyond the Crime SceneBeyond the Crime Scene

Search for evidence must extend to Search for evidence must extend to autopsy roomautopsy room

Medical examiner – determine CODMedical examiner – determine COD Tissues and organs retained for Tissues and organs retained for

pathological and toxicological pathological and toxicological examinationexamination

Medical examiner secures a variety Medical examiner secures a variety of items for investigator of items for investigator

Evidence the ME sends to Evidence the ME sends to InvestigatorInvestigator

Victim’s clothingVictim’s clothing Fingernail scrapingsFingernail scrapings Head and pubic hairsHead and pubic hairs Blood (for DNA analysis)Blood (for DNA analysis) Vaginal, anal, and oral swabs (sex-Vaginal, anal, and oral swabs (sex-

related crimes)related crimes) Recovered bullets from bodyRecovered bullets from body Hand swabs from shooting victims Hand swabs from shooting victims

(GSR)(GSR)

Interactive Autopsy AssignmentInteractive Autopsy Assignment

Go to this website and answer Go to this website and answer questions (given)questions (given)

http://www.hbo.com/autopsy/interacthttp://www.hbo.com/autopsy/interactive/ive/

Click on Interactive Autopsy to the Click on Interactive Autopsy to the right of the screenright of the screen

Collecting & Packaging Collecting & Packaging EvidenceEvidence

Goal: handle evidence so that there is least Goal: handle evidence so that there is least amount of change from CS to labamount of change from CS to lab

Potential problemsPotential problems ContaminationContamination BreakageBreakage EvaporationEvaporation Accidental scratching/breakingAccidental scratching/breaking Loss via carelessnessLoss via carelessness

Integrity = evidence kept intact (ex. Hair, Integrity = evidence kept intact (ex. Hair, soil should be left on clothing)soil should be left on clothing)

If evidence is found on large If evidence is found on large structure (door, wall)…structure (door, wall)… remove specimen with forcepsremove specimen with forcepsWith blood, scrape off surface, With blood, scrape off surface, transfer to moistened swab, or transfer to moistened swab, or cut out area bearing staincut out area bearing stain

Most Important Point About Most Important Point About Evidence CollectionEvidence Collection

Each different item or similar Each different item or similar items collected at different items collected at different locations must be placed in locations must be placed in separate containers!separate containers! Prevents damage through contactPrevents damage through contact Prevents cross contaminationPrevents cross contamination

Collecting EvidenceCollecting Evidence

Bag Bag

&&

TagTag

Tools for Evidence CollectionTools for Evidence Collection

Forceps (to pick up small items)Forceps (to pick up small items) Unbreakable plastic pill bottles w/ Unbreakable plastic pill bottles w/

pressure lidspressure lids Hairs, glass, fibers, other small trace Hairs, glass, fibers, other small trace

evidenceevidence Manila envelopes, screw-cap glass Manila envelopes, screw-cap glass

vials, metal/cardboard pill boxes also vials, metal/cardboard pill boxes also good for trace evidencegood for trace evidence

Small trace evidence and Small trace evidence and miscellaneous evidencemiscellaneous evidence

Ordinary mailing envelopes should Ordinary mailing envelopes should be avoidedbe avoided

Druggist folds are often used for Druggist folds are often used for small trancesmall trance Folding paper to produce closed Folding paper to produce closed

container, keeping specimen insidecontainer, keeping specimen inside Sealable plastic bags often universal Sealable plastic bags often universal

containercontainer

2 Exceptions to the Rule2 Exceptions to the Rule

Bloodstained materialsBloodstained materials Do NOT store in airtight containers!Do NOT store in airtight containers! Moisture builds up and allows for mold growthMoisture builds up and allows for mold growth Destroys evidentiary value of bloodDestroys evidentiary value of blood Use breathable paper envelopes or bagsUse breathable paper envelopes or bags

All clothing must be air dried and placed All clothing must be air dried and placed individually in separate bagsindividually in separate bags

Charred debris from a fire MUST be placed Charred debris from a fire MUST be placed in airtight container to prevent in airtight container to prevent evaporation of volatile petroleum residuesevaporation of volatile petroleum residues

Chain of CustodyChain of Custody

Chain of Custody = a list of all people who Chain of Custody = a list of all people who came into possession of an item of came into possession of an item of evidenceevidence

Must be established for use in courtMust be established for use in court Everyone must be accounted for!Everyone must be accounted for!

Each person must obtain written record of Each person must obtain written record of acquisition and dispositionacquisition and disposition

Each person may be required to testify in courtEach person may be required to testify in court If not, authenticity and integrity of If not, authenticity and integrity of

evidence is lostevidence is lost

Collecting Collecting Standard/Reference SamplesStandard/Reference Samples

Standard/Reference Sample:Standard/Reference Sample: Physical evidence whose origin is Physical evidence whose origin is known, such as blood or hair from known, such as blood or hair from a suspect, that can be compared a suspect, that can be compared to crime-scene evidenceto crime-scene evidence Can also be obtained from victimCan also be obtained from victim Paint from a hit-and-run vehiclePaint from a hit-and-run vehicle

Other ControlsOther Controls

Buccal SwabBuccal Swab – swab from the inner portion of – swab from the inner portion of the cheek, performed to collect cells for use in the cheek, performed to collect cells for use in determining the DNA profile of an individualdetermining the DNA profile of an individual

Substrate ControlSubstrate Control Uncontaminated surface material close to area Uncontaminated surface material close to area

where physical evidence has been depositedwhere physical evidence has been deposited Used to ensure that the surface on which a sample Used to ensure that the surface on which a sample

has been deposited does not interfere with lab has been deposited does not interfere with lab resultsresults

Used in arson cases – has surface been exposed to Used in arson cases – has surface been exposed to accelerant?accelerant?

Submit Evidence to LabSubmit Evidence to Lab

Delivered personally or by mail depending Delivered personally or by mail depending on case and urgencyon case and urgency Person familiar with casePerson familiar with case Can’t ship certain chemicals/live Can’t ship certain chemicals/live

ammo/explosivesammo/explosives Need evidence submission formNeed evidence submission form

Nature of crime, victim, case#, agency, Nature of crime, victim, case#, agency, investigatorinvestigator

Brief description of caseBrief description of case List of evidenceList of evidence What to investigate for each timeWhat to investigate for each time

Evidence Submission FormEvidence Submission Form

Murder Scene: Death and Murder Scene: Death and AutopsiesAutopsies

Questions a forensic pathologist may Questions a forensic pathologist may ask:ask: Who is the victim?Who is the victim? What injuries are present?What injuries are present? When did the injuries occur?When did the injuries occur? How and why were injuries produced?How and why were injuries produced?

Determining COD is primary role. If not known Determining COD is primary role. If not known externally, externally, AUTOPSYAUTOPSY is performed: Medical is performed: Medical dissection post-mortem to determine COD.dissection post-mortem to determine COD.

Review on Estimating TODReview on Estimating TOD

Rigor MortisRigor Mortis: Post mortem condition that : Post mortem condition that results in the stiffening of muscle massresults in the stiffening of muscle mass Manifests within 1Manifests within 1stst 24 hours; disappears within 24 hours; disappears within

36 hours36 hours Livor mortisLivor mortis: Post mortem condition that : Post mortem condition that

results in the settling of blood in areas results in the settling of blood in areas closest to groundclosest to ground Skin appears blue/purplishSkin appears blue/purplish Begins immediately after death and continues Begins immediately after death and continues

for up to 12 hours after deathfor up to 12 hours after death Was the victim’s position changed after death?Was the victim’s position changed after death?

Review on estimating TODReview on estimating TOD

Algor Mortis: Process by which the body Algor Mortis: Process by which the body temperature continually cools after temperature continually cools after death until it reaches the ambient death until it reaches the ambient temperaturetemperature

Beginning about 1 hour post mortem, Beginning about 1 hour post mortem, body loses 1-1.5 degrees F per hourbody loses 1-1.5 degrees F per hour Rate of heat loss depends on…Rate of heat loss depends on…

Location of bodyLocation of body Size of bodySize of body Victim’s clothingVictim’s clothing Weather conditionWeather condition

Another way to determine TODAnother way to determine TOD

Determine potassium (KDetermine potassium (K++) levels in ) levels in the ocular fluid in the eye (aka the ocular fluid in the eye (aka vitreous humor)vitreous humor)

After death, cells in the inner surface After death, cells in the inner surface of eyeball release Kof eyeball release K++ into ocular fluid into ocular fluid

Use rate of release of KUse rate of release of K++ to to determine TODdetermine TOD

Also…food in stomach = last mealAlso…food in stomach = last meal

Forensic AnthropologyForensic Anthropology

Identification of human skeletal Identification of human skeletal remainsremains

Bones are extremely durable and Bones are extremely durable and undergo slow breakdownundergo slow breakdown

Provide individual characteristics: sex, Provide individual characteristics: sex, age, race, injuryage, race, injury

Create facial reconstruction – to help Create facial reconstruction – to help IDID

Help ID in mass disasterHelp ID in mass disaster

Forensic AnthropologyForensic Anthropology

Forensic EntomologyForensic Entomology