16-1 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein FIREARMS, TOOL MARKS, AND OTHER IMPRESSIONS Forensic
Science - Chapter 16 Slide 2 16-2 2011, 2008 Pearson Education,
Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Famous People Killed /
Wounded with Guns Abraham Lincoln John Lennon John F. Kennedy
Robert F. Kennedy Martin Luther King Jr. Pope John Paul ll Mohandas
Ghandi Franz Ferdinand Malcolm X Bob Marley Ronald Reagan Theodore
Roosevelt 50 Cent The Notorious B.I.G. Tupac Shakur Sean Taylor
Slide 3 16-3 2011, 2008 Pearson Education, Inc. Upper Saddle River,
NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein Introduction Structural variations and irregularities
caused by scratches, nicks, breaks, and wear may permit the
criminalist to relate: A bullet to a gun A scratch or abrasion mark
to a single tool A tire track to a particular automobile
Individualization, a goal of in all areas of criminalistics,
frequently becomes an attainable reality in firearm and tool mark
examination. Slide 4 16-4 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Father of Ballistics Calvin Goddard,
physician, acquired data from all known gun manufacturers in order
to develop a comprehensive database.Calvin Goddard Slide 5 16-5
2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458
FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein
Charles Waite - Goddard his partner, Charles Waite, he catalogued
the results of test-firings from every type of handgun made by 12
manufacturers. Waite also invented the comparison microscope. With
this instrument, two bullets could be laid adjacent to one another
for comparative examination. comparison microscope Slide 6 16-6
2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458
FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein
TERMINOLOGY OF GUNS Due to the multiple types, purposes, and
cultures that have developed around firearms, a language of its own
has developed. Before discussing the forensics of firearms, one
must have a grasp on the terminology associated with guns. We will
look at different types of guns and their parts and uses. Slide 7
16-7 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein TYPES OF GUNS Modern firearms are manufactured in a
variety of shapes and sizes to fit multiple purposes. These include
semi-automatic and even automatic weapons built primarily for
military usage. Virtually any type of gun can be found on the
streets in use by youth gangs, persons involved in drug
trafficking, "survivalists", and even what we would consider
"ordinary" citizens. Slide 8 16-8 2011, 2008 Pearson Education,
Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein HANDGUNS A handgun was
conceived as a compact weapon for self defense. The two most common
defensive handguns are the double action revolver and the
semiautomatic pistol. Slide 9 16-9 2011, 2008 Pearson Education,
Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein REVOLVERS The revolver
is the older type of handgun. It is less expensive, easy to use,
simpler in design, and more reliable than semiautomatics. However,
compared to semiautomatic weapons, revolvers are limited to six
shots, relatively slow to reload, less efficient, and the trigger
pull is more difficult. Slide 10 16-10 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Revolvers The
revolver, the first multiple shot hand gun, has several advantages
they are less expensive, simpler in design, and more reliable than
semiautomatics. A revolver is easy to use and are accurate.
However, compared to semiautomatic weapons, revolvers are limited
to six shots, relatively slow to reload, less efficient, and the
trigger pull is more difficult. Slide 11 16-11 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Handguns Revolver
Slide 12 16-12 2011, 2008 Pearson Education, Inc. Upper Saddle
River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By
Richard Saferstein Parts of a Handgun Slide 13 16-13 2011, 2008
Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC
SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Revolvers
Parts If the barrel length is shorter, for ease of concealment, the
gun becomes less accurate in hitting the target. An ejector rod
under the barrel is used to eject fired cartridges from the open
cylinder before reloading. The sights, which are lined up when
aiming the weapon, on a revolver are usually a blade in the front
and a notch on the rear. Slide 14 16-14 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Revolver Parts
Continued The frame is the largest part, and all other pieces
attach to it. Frames are usually made of blued or plated steel,
stainless steel, or lightweight alloys such as magnesium. The
cylinder contains five or six holes for the cartridges and can be
swung out for reloading. This must performed manually; the absence
of cartridge cases at a crime scene may indicate the use of a
revolver. Slide 15 16-15 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Parts of Revolver Continued On a revolver,
there is a gap between the cylinder and barrel to allow the
cylinder to turn freely, this also allows gases and gun powder
residue to escape laterally and allow the forensic pathologist to
predict the location of a shooter more easily. The inner mechanics
of a revolver uses the energy from a trigger pull to rotate the
cylinder, cocking the weapon, and then fall the hammer. Slide 16
16-16 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein Revolver Parts continued Revolver with cylinder out for
reloading Old Wild West Colt 45 Slide 17 16-17 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Revolver Firing
Mechanism Revolvers can have one of two distinct firing action
designs. A single-action revolver, the oldest and simplest action,
requires a shooter to cock the hammer back before each pull of the
trigger. SLOW. In a double-action weapon, a trigger pull will cock
the weapon manually and fire the gun. This requires quite a bit
more pressure and may compromise accuracy. Slide 18 16-18 2011,
2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC
SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein
Semiautomatic Pistol A more recent development than the revolver
the pistol originated in the late 19th century. The advantages of
semiautomatics stem from the use of recoil generated by the fired
cartridge to eject the empty cartridge case, load the next
cartridge, and cock the hammer. This is more conducive to firing
multiple shots at multiple speeds. Many pistols are designed to
carry 15 to 19 rounds. Slide 19 16-19 2011, 2008 Pearson Education,
Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Handguns
Semi-automatic Courtesy of C. Fanning Slide 20 16-20 2011, 2008
Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC
SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein
Semiautomatic Pistol Disadvantes Disadvantages: A more complicated
mechanism requires more practice to use accurately, and is more
likely to malfunction. In addition, cartridge cases must be shorter
to work well; because of this revolver cartridges are more powerful
than semiautomatic cartridges. Slide 21 16-21 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Parts of a Semi-auto
Handgun Slide 22 16-22 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Parts of a Semi-auto Pistol Slide 23 16-23
2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458
FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein
Rifle Types Rifles differ from handguns in the length of the barrel
and the presence of a butt stock. They are harder to carry, are
poorly concealable, and more loosely regulated than handguns.
However, they are much more accurate and shoot more powerful
cartridges than handguns. Rifles may be manufactured as single
shot; but, most commonly rifles possess bolt action, like. Military
rifles are semiautomatic or automatic, having a detachable magazine
holding 5 to 50 rounds. Slide 24 16-24 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Rifle Types Old
Fashion Lever type rifle. Bolt action hunting rifle Semi- automatic
hunting rifle Slide 25 16-25 2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2
nd ed. By Richard Saferstein Muzzleloading Rifle Slide 26 16-26
2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458
FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein
Parts of a Bolt Action Rifle Slide 27 16-27 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein AUTOMATIC RIFLES
Automatic weapons are those weapons which will fire repeated rounds
when the trigger is pulled and held. This allows the weapon to
fire, reload and fire again as fast as the gun can possibly move.
The most widely know automatic weapons are machine guns. Most of
these weapons are not legal, for personal use. It is possible for a
skilled gunsmith to convert a semiautomatic into a fully automatic
weapon. Slide 28 16-28 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Parts of a Semiautomatic Rifle M1 carbine
will fire each time you pull the trigger without manually
reloading. The shells are held in the vertical clip under the
receiver. Slide 29 16-29 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein ASSAULT WEAPONS Assault weapons are those
weapons designed to kill mass numbers of people at a time. The
classification includes automatic weapons, machine guns, sawed off
shotguns, grenade launchers, and many other weapons used by the
military. Slide 30 16-30 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Automatic Assault Rifles The most deadly gun
that is commonly hand carried by the shooter. It can fire many
rounds without reloading; as fast as you can pull the trigger and
can be set to fully automatic mode. Slide 31 16-31 2011, 2008
Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC
SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Ballistic
Fingerprinting Ballistic fingerprinting refers to a set of forensic
techniques that rely on marks that firearms leave on bullets to
match a bullet to the gun it was fired with.
forensicfirearmsbullets Slide 32 16-32 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Gun Barrel Markings
The inner surface of the barrel of a gun leaves its markings on a
bullet passing through it. These markings are peculiar to each gun.
The gun barrel is produced from a solid bar of steel that has been
hollowed out by drilling. The microscopic drill marks left on the
barrels inner surface are randomly irregular and serve to impart a
uniqueness to each barrel. Slide 33 16-33 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Bullet Recovery Tank
Each gun submitted is test fired and the recovered bullets and
cartridge cases are retained for use in further analysis. Slide 34
16-34 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein Recovered Bullets Slide 35 16-35 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein The Bore of Guns Slide
36 16-36 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein Gun Barrel Markings The manufacture of a barrel also
requires impressing its inner surface with spiral grooves, a step
known as rifling. The surfaces of the original bore remaining
between the grooves are called lands. The grooves serve to guide a
fired bullet through the barrel, imparting a rapid spin to insure
accuracy. Slide 37 16-37 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Riflings in a Barrell Riflings are the groves
that cause a bullet to spin and gain stability for a more accurate
shot Slide 38 16-38 2011, 2008 Pearson Education, Inc. Upper Saddle
River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By
Richard Saferstein Lands and Grooves Groove Land Diameter Caliber
Slide 39 16-39 2011, 2008 Pearson Education, Inc. Upper Saddle
River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By
Richard Saferstein Gun Barrel Markings The diameter of the gun
barrel, measured between opposite lands, is known as caliber. Most
older guns calibers are measured in fraction of inches across the
islands. So a 45 caliber bullet is 0.45 inches across. Some newer
bullets are measured in millimeters. Once a manufacturer chooses a
rifling process, the class characteristics of the weapons barrel
will remain consistent, each will have the same number of lands and
grooves, with the same approximate width and direction of twist.
Slide 40 16-40 2011, 2008 Pearson Education, Inc. Upper Saddle
River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By
Richard Saferstein Striations Striations, which are fine lines
found in the interior of the barrel, are impressed into the metal
as the negatives of minute imperfections found on the rifling
cutters surface, or they are produced by minute chips of steel
pushed against the barrels inner surface by a moving broach cutter.
These striations form the individual characteristics of the barrel.
Slide 41 16-41 2011, 2008 Pearson Education, Inc. Upper Saddle
River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By
Richard Saferstein Bullet Striations from the Barrel The striations
on the bullet can make identifiable and unique markings that trace
it back to a particular firearm. Slide 42 16-42 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Striations It is the
inner surface of the barrel of a gun that leaves its striation
markings on a bullet passing through it. Courtesy of C. Fanning
Slide 43 16-43 2011, 2008 Pearson Education, Inc. Upper Saddle
River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By
Richard Saferstein Bullet Examination No two rifled barrels, even
those manufactured in succession, will have identical striation
markings. The number of lands and grooves and their direction of
twist are obvious points of comparison during the initial stages of
an examination between an evidence bullet and a test-fired bullet.
Any differences in these class characteristics immediately serve to
eliminate the possibility that both bullets traveled through the
same barrel. Slide 44 16-44 2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2
nd ed. By Richard Saferstein The Comparison Microscope The
comparison microscope serves as the single most important tool to a
firearms examiner. Two bullets can be observed and compared
simultaneously within the same field of view. Not only must the
lands and grooves of the test and evidence bullet have identical
widths, but the longitudinal striations on each must coincide.
Slide 45 16-45 2011, 2008 Pearson Education, Inc. Upper Saddle
River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By
Richard Saferstein Comparison of Bullet Marks Slide 46 16-46 2011,
2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC
SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Calibers
of Bullets Slide 47 16-47 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Caliber of Gun Bores Slide 48 16-48 2011,
2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC
SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Machine
Guns Fully automatic machine guns can fire up to 1200 bullets per
minute. Slide 49 16-49 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Rapid Fire Machine Gun Typical cyclic rates
of fire are 500900 RPM for assault rifles, 900-1,200 RPM for
submachine guns and machine pistols, and 600-1,200 RPM for machine
guns. M134assault riflessubmachine gunsmachine pistolsmachine
gunsM134 Slide 50 16-50 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein SHOTGUNS Shotguns have a similar external
appearance to rifles, but differ in the lack of rifling inside the
barrel, which is the basis for their legal definition. A shotgun
shell may contain one large projectile (called a slug), a few
pellets of large shot, or many tiny pellets. Shotguns are available
in single shot (break action), double barrel, pump action, and
semiautomatic. Unlike rifled firearms, a shotgun has a smooth
barrel. Slide 51 16-51 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Shotguns Shotguns have a similar external
appearance to rifles, but differ in the lack of rifling inside the
barrel, which is the basis for their legal definition Unlike rifled
firearms, a shotgun has a smooth barrel. Shotguns generally fire
small lead balls or pellets that are not impressed with any
characteristic markings that can be related back to the weapon.
Slide 52 16-52 2011, 2008 Pearson Education, Inc. Upper Saddle
River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By
Richard Saferstein SHOTGUNS - GAUGE The diameter of the shotgun
barrel is expressed by the term gauge. In the lower numbered
gauges, it is the number of pellets that are needed to span the
internal barrel diameter. The higher the gauge number, the smaller
the barrels diameter. Slide 53 16-53 2011, 2008 Pearson Education,
Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein SHOTGUNS The truly
unique thing about shotguns stems from the shot that is projected
from the barrel and the distribution pattern as it approaches a
target. The original intent of such a design was to lesson the
skill needed to shoot small moving food targets, such as birds and
rabbits. Although these guns are still commonly used for such
purposes, criminals, gangs, and even law enforcement uses them.
Slide 54 16-54 2011, 2008 Pearson Education, Inc. Upper Saddle
River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By
Richard Saferstein Shotgun & Shells Slide 55 16-55 2011, 2008
Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC
SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Shotgun
Impact Patterns The firing distances involving shotguns must again
be related to test firing. The muzzle to target distances can be
established by measuring the spread of the discharged shot. Slide
56 16-56 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein Reloading Shotguns Semi- automatic ejection out the side
of the reciever Breechloading Slide 57 16-57 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Firing a Weapon The
act of pulling the trigger serves to release the weapons firing
pin, causing it to strike the primer, which in turn ignites the
powder. The expanding gases generated by the burning gunpowder
propel the bullet forward through the barrel, simultaneously
pushing the spent cartridge case or shell back with equal force
against the breechblock. Slide 58 16-58 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Firing a Weapon The
shell is impressed with markings by its contact with the metal
surfaces of the weapons firing and loading mechanisms. Slide 59
16-59 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein Anatomy of a Shell Slide 60 16-60 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Cartridge Case
Comparison The firing pin, breechblock, and ejector and extractor
mechanism also offer a highly distinctive signature for
individualization of cartridge cases. Courtesy of C. Fanning Slide
61 16-61 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein Cartridge Case Comparison The shape of the firing pin
will be impressed into the relatively soft metal of the primer on
the cartridge case. The cartridge case, in its rearward thrust, is
impressed with the surface markings of the breechblock. Slide 62
16-62 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein Cartridge Case Comparison Other distinctive markings
that may appear on the shell as a result of metal to metal contact
are caused by the: Ejector, which is the mechanism in a firearm
that throws the cartridge or fired case from the firearm.
Extractor, which is the mechanism in a firearm by which a cartridge
of a fired case is withdrawn from the firing chamber. Magazine or
clip, which is the mechanism that in a firearm holds the bullets.
Slide 63 16-63 2011, 2008 Pearson Education, Inc. Upper Saddle
River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By
Richard Saferstein Computerized Imaging The advent of computerized
imaging technology has made possible the storage of bullet and
cartridge surface characteristics in a manner analogous to
automated fingerprint files. Slide 64 16-64 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Computerized Imaging
The National Integrated Ballistics Information Network, NIBIN,
produces database files from bullets and cartridge casings
retrieved from crime scenes or test fires from retrieved firearms,
often linking a specific weapon to multiple crimes. It is important
to remember, however, that the ultimate decision for making a final
comparison will be determined by the forensic examiner through
traditional microscopic methods. Slide 65 16-65 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein NIBIN Slide 66 16-66
2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458
FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein
Gunpowder Residue When a firearm is discharged, unburned and
partially burned particles of gunpowder in addition to smoke are
propelled out of the barrel along with the bullet toward the
target. If the muzzle of the weapon is sufficiently close, these
products will be deposited onto the target. The distribution of
gunpowder particles and other discharge residues around a bullet
hole permits an assessment of the distance from which a handgun or
rifle was fired. Slide 67 16-67 2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2
nd ed. By Richard Saferstein Gunpowder Residue The precise distance
from which a handgun or rifle has been fired must be determined by
means of a careful comparison of the powder- residue pattern
located on the victims clothing or skin against test patterns made
when the suspect weapon is fired at varying distances from a
target. By comparing the test and evidence patterns, the examiner
may find enough similarity in shape and density upon which to base
an opinion as to the distance from which the shot was fired. Slide
68 16-68 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein Gunpowder Residue Detection Slide 69 16-69 2011, 2008
Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC
SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Gunpowder
Residue In cases where the weapon is held in contact with or less
than 1 inch from the target, a star- shaped (stellate) tear pattern
around the bullet hole entrance, surrounded by a rim of a smokeless
deposit of vaporous lead is usually present. A halo of vaporous
lead (smoke) deposited around a bullet hole is normally indicative
of a discharge of 12 to 18 inches or less. This deposits on the
hands of a shooter and can be chemically analyzed for proof of
shooting a gun. Slide 70 16-70 2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2
nd ed. By Richard Saferstein Gun Powder Residue around Wounds Slide
71 16-71 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein Gunpowder Residue The presence of scattered specks of
unburned and partially burned powder grains without any
accompanying soot is often observed at distances up to 25 inches
(and occasionally as far as 36 inches). More than 3 feet, will
usually not deposit any powder residues, and the only visual
indication is a dark ring around the hole, known as a bullet wipe.
Slide 72 16-72 2011, 2008 Pearson Education, Inc. Upper Saddle
River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By
Richard Saferstein Gunpowder Residue When garments or other
evidence relevant to a shooting are received in the crime
laboratory, the surfaces of all items are first examined
microscopically for the presence of gunpowder residue. Chemical
tests, such as the Greiss test, may be needed to detect gunpowder
residues that are not visible. Atomic Absorption spectroscopy is
also used to prove the presence of gun powder residue. Slide 73
16-73 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein Griess Test The Griess test is a chemical analysis test
which detects the presence of organic nitrite compounds. The Griess
diazotization reaction on which the Griess reagent relies was first
described in 1858 by Peter Griess.chemicalanalysisorganic
nitritePeter Griess Slide 74 16-74 2011, 2008 Pearson Education,
Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Powder Residue on
Clothing Slide 75 16-75 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Primer Residue on Hands The firing of a
weapon not only propels residues toward the target, but gunpowder
and primer residues are also blown back toward the shooter. As a
result, traces of these residues are often deposited on the firing
hand of the shooter, and their detection can provide valuable
information as to whether or not an individual has recently fired a
weapon. Slide 76 16-76 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Primer Residue on Hands Examiners measure the
amount of barium and antimony on the relevant portion of the
suspects hands, such as the thumb web, the back of the hand, and
the palm. Slide 77 16-77 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Primer Residue on Hands They may also
characterize the morphology of particles containing these elements
to determine whether or not a person has fired, handled a weapon,
or was near a discharged firearm. Slide 78 16-78 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Serial Numbers Serial
numbers are used to trace the ownership of a gun to a suspect or
source. Increasingly, the criminalist is requested to restore a
serial number when it has been removed or obliterated by grinding,
rifling, or punching. Restoration of serial numbers is possible
through chemical etching because the metal crystals in the stamped
zone are placed under a permanent strain that extends a short
distance beneath the original numbers. Slide 79 16-79 2011, 2008
Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC
SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Serial
Numbers on Guns Slide 80 16-80 2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2
nd ed. By Richard Saferstein Firearm Evidence Collection Firearms
are collected by holding the weapon by the edge of the trigger
guard or by the checkered portions of the grip. Before the weapon
is sent to the laboratory, all precautions must be taken to prevent
accidental discharge of a loaded weapon. In most cases, it will be
necessary to unload the weapon. Slide 81 16-81 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Firearm Evidence
Collection When a revolver is recovered, the chambers, their
positions, and corresponding cartridges must be recorded. Firearm
evidence must be marked for identification (usually a tag on the
trigger guard) and a chain of custody must be established. Slide 82
16-82 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein Firearm Evidence Collection Bullets recovered at the
crime scene are scribed with the investigators initials, either on
the base or the nose of the bullet. The obliteration of striation
markings that may be present on the bullet must be scrupulously
avoided. The investigator must protect the bullet by wrapping it in
tissue paper before placing it in a pillbox or an envelope for
shipment to the crime laboratory. Slide 83 16-83 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Firearm Evidence
Collection Fired casings must be identified by the investigators
initials placed near the outside or inside mouth of the shell.
Discharged shotgun shells are initialed on the paper or plastic
tube remaining on the shell or on the metal nearest the mouth of
the shell. Slide 84 16-84 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Different Tools / Guns Tools of all types
will leave marks that can be traced back to a source in criminal
forensics. Slide 85 16-85 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Tool Marks A tool mark is considered to be
any impression, cut, gouge, or abrasion caused by a tool coming
into contact with another object. A careful examination of the
impression can reveal important class characteristics, such as the
size and shape of the tool. Slide 86 16-86 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Tool Marks But it is
the presence of any minute imperfections on a tool that imparts
individuality to that tool. The shape and pattern of such
imperfections are further modified by damage and wear during the
life of the tool. Slide 87 16-87 2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2
nd ed. By Richard Saferstein Tool Marks The comparison microscope
is used to compare crime-scene toolmarks with test impressions made
with the suspect tool. When practical, the entire object or the
part of the object bearing the tool mark should be submitted to the
crime laboratory for examination. Slide 88 16-88 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Tool Marks Under no
circumstances must the crime scene investigator attempt to fit the
suspect tool into the tool mark. Any contact between the tool and
the marked surface may alter the mark and will, at the least, raise
serious questions about the integrity of the evidence. Slide 89
16-89 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein Tool marks on bones Tool marks on bones can identify the
type of tool that was used in the crime and may isolate it down to
individual evidence for a trial. Slide 90 16-90 2011, 2008 Pearson
Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE : An
Introduction, 2 nd ed. By Richard Saferstein Other Impressions
Impressions of other kinds, such as shoe, tire or fabric
impressions, may be important evidence. Before any impression is
moved or otherwise handled, it must be photographed (including a
scale) to show all the observable details of the impression. If the
impression is on a readily recoverable item, such as glass, paper,
or floor tile, the evidence is transported intact to the
laboratory. Slide 91 16-91 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Footprints and Tire Marks Slide 92 16-92
2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458
FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein
Other Impressions If the surface cannot be submitted to the
laboratory, the investigator may be able to preserve the print in a
manner similar to lifting a fingerprint. Slide 93 16-93 2011, 2008
Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC
SCIENCE : An Introduction, 2 nd ed. By Richard Saferstein Other
Impressions When shoe and tire marks are impressed into soft earth
at a crime scene, their preservation is best accomplished by
photography and casting. In areas where a bloody footwear
impression is very faint or where the subject has tracked through
blood leaving a trail of bloody impressions, chemical enhancement
can visualize latent or nearly invisible blood impressions. Slide
94 16-94 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ
07458 FORENSIC SCIENCE : An Introduction, 2 nd ed. By Richard
Saferstein Points of Comparison A sufficient number of points of
comparison or the uniqueness of such points will support a finding
that both the questioned and test impressions originated from one
and only one source. New computer software and web sites may be
able to assist in making shoe print and tire impression
comparisons. Also, bite mark impressions on skin and foodstuffs
have proven to be important evidence in a number of homicide and
rape cases. Slide 95 16-95 2011, 2008 Pearson Education, Inc. Upper
Saddle River, NJ 07458 FORENSIC SCIENCE : An Introduction, 2 nd ed.
By Richard Saferstein Bitemarks and Computer Analysis
