Running head: BALLISTICS IDENTIFICATION: FROM DISCHARGE TO CONVICTION HOW CSI’S SEE THE SECRETS
Ballistics Identification: From discharge to conviction how CSI’s see the secrets
Drew McIntosh
Florida Southern College
Abstract
With television shows exploiting law enforcement and science, criminals think that they are
capable of out thinking the police and crime scene investigators by attempting to leave no trace
evidence behind at a crime scene. Crimes that are committed with the use of guns are sometimes
hard to solve. The reason for this paper is to explain the process and capability Crime Labs have
to link bullets and shell casing to guns and suspects. This paper will also go in depth on bullet
striation marks, how they are caused, and unique to each firearm. This paper will also look at the
process of comparing bullets using technology and databases that law enforcement have at their
disposal. This data is important information which can help investigators link criminals, guns,
and motives based on bullets found at crime scenes.
Ballistics Identification: From discharge to conviction how CSI’s see the secrets
BALLISTICS IDENTIFICATION: FROM DISCHARGE TO CONVICTION HOW CSI’S SEE THE SECRETS
From the time that a crime is committed every second counts while a suspect is on the
loose. For the men and women of law enforcement, the evidence that is left behind holds clues
and secrets that individuals do not realize they leave. During the commission of a crime
involving a gun, the bullet holds many clues that can point the police in the direction of a
suspect. This paper will show the physical clues that are left behind by the shooter and how
Crime Scene Investigators use science and technology to find the shooter.
When a shot rings out there is a very short yet lengthy process inside the framework of a
gun. From the firing pin hitting the bullet’s primer causing the projectile to travel through the
barrel leaving striations and grooves to be imprinted at microscopic levels that can link a firearm
to a shooter. This paper will also explain how a gun can be linked to a bullet by the grooves and
striations, and when a bullet is found at a crime scene how the Crime Scene Investigator will
process the bullet in the lab with the comparison microscope process to see two bullets at one.
Guns are very complex machines that are comprised of hundreds of parts. Picking up a
gun and not knowing how to properly use it may result in great bodily harm. However, picking
up the gun may be all investigators need to link a suspect with a weapon. Every time we hold or
touch an item we leave behind a very unique pattern called fingerprints. Fingerprints are created
when oils and residues on your fingers are transferred from the peaks of friction ridges to a
relatively smooth surface (Young and Ortmeier, 2011). Each finger in a human fingerprint is
unique. When a person uses a gun, they perform a variety of functions and movements in order
to allow the gun to fire. This means a person touches a multitude places on the gun possibly
leaving behind fingerprints. Gripping a firearm exposes the fingers of the gripping hand to the
handle of the gun. Pulling the trigger reveals portions of the index finger and touching the slide
or other parts of the gun can expose even more fingerprints of a suspect. A fingerprint may be
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BALLISTICS IDENTIFICATION: FROM DISCHARGE TO CONVICTION HOW CSI’S SEE THE SECRETS
found on the magazine and the bullets inside the magazine. Fingerprints can either be seen by the
naked eye or with the assistance of fingerprint powder. Once a print has been processed with a
powder or a chemical, it becomes a latent fingerprint (Young and Ortmeier, 2011). Since
fingerprints are unique to each human it allows investigators to run the fingerprints lifted from a
firearm through a database composed of thousands of fingerprints. This database is called AFIS
or Automated Fingerprint Identification System. The database is comprised of millions of known
and unknown fingerprints. The database also consists of some palm prints. Automated
Fingerprint Identification System stores the pattern type and the relationship of the minutiae in
the fingerprints (Young and Ortmeier, 2011). The program uses an algorithm to identify
similarities between fingerprints (Young and Ortmeier, 2011).
When a CSI takes fingerprints from a suspect or a victim that is involved in a case they
will place the fingerprints on a 10-print card. This is a standard card that was designed to create
uniformity among agencies when collecting fingerprints. These cards are then scanned into AFIS
to be matched against those from other crimes, employment, licensing and non-criminal activity.
In certain situations that fingerprints need to be matched on a federal level, the FBI has a
computer program that allows agencies remote access courtesy of the Integrated Automated
Fingerprint Identification System (IAFIS) (Young and Ortmeier, 2011).
When fingerprints are left behind so are small microscopic skin cells that hold
deoxyribonucleic acid commonly referred to as DNA. Forensic Investigators can send samples
to be tested for touch DNA to see if there is a match in the system (Bode, 2010). Touch DNA is a
process that amplifies the DNA present and creates a profile that is able to be compared to others
profiles that have been compiled. Touch DNA’s process is similar to those of semen, saliva,
blood; therefore, allowing touch DNA to be admissible into a court of law (Bode, 2010). Touch
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BALLISTICS IDENTIFICATION: FROM DISCHARGE TO CONVICTION HOW CSI’S SEE THE SECRETS
DNA can be sampled from objects that are hard surfaced with a swab but samples can also be
soft like cloth. These samples are run using the amplification process creating a profile (Bode,
2010).
A way to identify DNA is through the Combined DNA Index System also known as
CODIS. CODIS was created by the Federal Bureau of Investigations seeking to help
investigators with identifying suspects by providing computer programs to conduct DNA
matches (Loftus, 1999). CODIS enables local, state, and federal law enforcement crime labs to
exchange and compare DNA profiles (Loftus, 1999). CODIS organizes and profiles DNA
samples into indexes. These indexes include: Convicted Offender, Forensic Index, Population
Index, Victim Index, Unidentified Persons Index, and Unidentified Persons Reference Index
(Loftus, 1999).
When a DNA samples is collected from a crime scene, the samples’ profile can be added
to CODIS allowing the system an opportunity to find matches. If a match is found the two
agencies will confirm the match and then share information about the potential suspect.
Outside of the databases for external forensic evidence, the internal instruments of the
gun are very important when investigators are looking at how to identify the weapon. When
performing an examination the technician will follow a very tight protocol to make sure the
firearm is handled properly. When comparing firearms there is a detailed multilevel analysis
each firearm goes through. In level-one the examiner will first receive a suspect’s firearm along
with bullets (projectile) and spent casings that were recovered from a crime scene or search. The
examiner will compile a comparison sample by test firing the weapon. This test firing bullets and
casings will serve as a control for the firearm (Bunch et. al., 2009). If a level-one examination
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BALLISTICS IDENTIFICATION: FROM DISCHARGE TO CONVICTION HOW CSI’S SEE THE SECRETS
fails to eliminate a firearm a level-two analysis is performed. A level-two will involve the
comparison of the smaller microscopic features on the projectile.
The main piece of equipment that investigators use for examining ballistics is a forensic
comparison microscope. A forensic comparison microscope is comprised of two microscopes
that are connected by an optical bridge. The optical bridge allows the examiner to utilize one
eyepiece and examine two microscope stages with a spilt screen. Comparison microscopes are
built with a variety of accessories to allow investigators to attach bullets, cartridge cases, firearm
parts, and shot rounds. The microscope will have a video imaging system attached so that the
investigation will be able to see how the comparison is made for court records (Mozayani &
Noziglia, 2010).
The firearms examiner will be looking at a multitude of identifiers to determine whether
the gun is a marked as identified or as an eliminated firearm. Each gun when manufactured is
microscopically different from other guns. When using the forensic comparison microscope the
examiner will identify a firearm from the firing pin, the head stamp, the striations and grooves
(Young and Ortmeier, 2011). Grooves are created by the projectile traveling through the barrel.
The areas between the grooves are considered “lands” (Mozayani & Noziglia, 2010). These
identification marks are present in handguns, and long guns excluding most shotguns. The
grooves create a spin on the bullet as it is discharged from the barrel (Mozayani & Noziglia,
2010). The spin created by the barrels grooves stabilizes the bullet improving accuracy
(Mozayani & Noziglia, 2010). Each firearm has a specific number of lands and grooves which
are class characteristics for the make and model of the weapon (Mozayani & Noziglia, 2010).
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BALLISTICS IDENTIFICATION: FROM DISCHARGE TO CONVICTION HOW CSI’S SEE THE SECRETS
In the early 1990s the Federal Bureau of Investigation (FBI) and the Bureau of Alcohol,
Tobacco, and Firearms (ATF) both created and implemented database that could store
information relative to expended projectiles and cartridge casings (Young and Ortmeier, 2011).
The FBI designed DRUGFIRE while the ATF created the Integrated Ballistics Identifications
system (IBIS) (Young and Ortmeier, 2011). Any comparison that was made in a lab would be
entered into the system however with two different databases there was difficulty entering
information into both systems. In 1999, the FBI and ATF both compiled their databases forming
the National Integrated Ballistics Information Network (NIBIN) (Young and Ortmeier, 2011).
IBIS/NIBIN is the AFIS of bullets and firearms. The database will store, compare, and retrieve
information from state/local representatives, federal agencies (Mozayani & Noziglia, 2010).
The first case using bullet comparison was an 1879 Virginia appellate case Dean v.
Commonwealth, where the court approved the testimony regarding the resemblances between
fatal and test bullets (Inbau, 1999). In 1993 the Supreme court in Daubert v. Merrell Dow
Pharmaceuticals that the expert testimony must be related to a verifiable science. In relation to
firearms identification, the examination of evidence is based on patterns and pattern recognition.
There is no science behind testimony except for training and experience. Firearm comparison
often comes under attacked due to the lack of research proving an exact science. This dilemma
with the courts has unleashed many studies behind ballistics identification. In 2006, a federally
funded study by Benjamin Bachrach was started to prove that there was an exact science behind
the examination. Bachrach found that using a computer and 3D imaging, he could create an
analytical score based of the striations. The computer determines whether or not the bullets are a
match (Mozayani & Noziglia, 2010).
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BALLISTICS IDENTIFICATION: FROM DISCHARGE TO CONVICTION HOW CSI’S SEE THE SECRETS
Beyond the internal parts of a firearm, there are other ways to find out who the owner or
person who bought the firearm is. Each gun that is sold has a unique serial number that is
specific just to that individual gun (Mozayani & Noziglia, 2010; Young and Ortmeier, 2011).
These serial numbers are located in different locations on firearms. Most commonly serial
numbers can be found on the barrel of the firearm as well as underneath the opening of the barrel
on the polymer handle of the gun (Mozayani & Noziglia, 2010). The first step in restoring a
serial number is to polish the surface where the serial number was removed. The polishing
allows contrast between compressed and uncompressed areas (Mozayani & Noziglia, 2010). The
next step is to add a specific chemical onto the area and attach an electrical current to the metal
to speed up the reaction. Other methods available are using heat to turn the metal red hot and
watching the cooling patterns to visibly see the serial number (Mozayani & Noziglia, 2010).
There are some techniques where a ultrasonic bath is used. This process is similar to the
chemical process .Once the restoration is complete, the serial number can be run through the
manufactures databases to see where the gun was sold and who purchased the gun (Mozayani &
Noziglia, 2010).
There are many ways in which a CSI can identify a shooter; in some cases it is easier than
others. Though many of these processes are used in crime labs across the globe, researchers are
working on ways to improve these techniques. While criminals get smarter and try to cover up
crimes thanks to knowledge from TV and the internet, the research is improving processes to
prevent criminals from getting away with crime. Science is always looking for ways to improve
DNA testing. Gun manufactures are looking for the latest and greatest parts that are unique that
criminals would not be able to corrupt. The men and women of law enforcement know thorough
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BALLISTICS IDENTIFICATION: FROM DISCHARGE TO CONVICTION HOW CSI’S SEE THE SECRETS
crime scene investigation combined with science leads to clues that will guide them to the
criminal if they listen to the evidence.
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BALLISTICS IDENTIFICATION: FROM DISCHARGE TO CONVICTION HOW CSI’S SEE THE SECRETS
Literature Cited
Bode Technology. (2010). Touch dna. Retrieved from http://www.bodetech.com/forensicsolutions/dna-technologies/touch-dna/
Inbau, F. (1999). Firearm identification- "ballistics". Journal of criminal law & criminology,
89(4), 1293-1314.
Loftus, P. (1999). Dna typing in corrections. Corrections today, 61(4), 68-71.
Mozayani, A., & Noziglia, C. (2010). The forensic laboratory handbook: Procedures and
practice. New York: Springer Science.
Young, T., and P. J. Ortmeier. Crime scene investigation. New York, NY: Prentice Hall, 2011.
Print.
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