Firearms and Tool Mark
The Firearms and Tool Mark Section is under the direction of Special Agent in Charge Pete Ware. The primary responsibility of the Firearm and Tool Mark Section of the SBI Crime Laboratory in Raleigh is the examination and comparison of bullets, cartridge cases and shotgun shells to determine if they were fired in or from a particular firearm. This examination and comparison is part of the forensic discipline known as Firearms Identification. Firearms Identification is often mistakenly called Ballistics. Ballistics is the study of projectiles in motion and does encompass some of a Firearm Examiner's duties but is not the main focus of the Section. There are no college courses of study to teach someone to become proficient in Firearms Identification. In the SBI, training is received on the job, through a structured training curriculum administered by Senior Firearm Examiners.
In
order to match a bullet to a particular firearm a Firearm Examiner looks for
two criteria. These are class characteristics and individual characteristics.
Class characteristics are measurable features of a specimen that indicate
a restricted group source. On bullets the class characteristics of interest
to the Firearm Examiner are the rifling specifications of the barrel from
which the bullet was fired. These include caliber, number of lands and grooves,
direction of twist of the lands and groves, and widths of the lands and grooves.
If an evidence bullet and test bullets fired from a suspect firearm have the
same class characteristics, the Firearm Examiner can conclude that the evidence
bullet could have been fired from the suspect firearm. Individual characteristics
are marks unique only to that particular firearm barrel. In a barrel the individual
characteristics are produced by the random imperfections and irregularities
of the tool or tools used to produce the lands and grooves and by use, corrosion
or damage. If an evidence bullet has the same class characteristics and matching
individual characteristics to test bullets fired from a suspect firearm, the
Firearm Examiner can conclude that the bullet was fired from the suspect
firearm.
A
Firearm Examiner must also be skilled in firearm function. An examiner
needs to know and understand the various types of firearms and the types of
actions employed by the firearms manufacturers in producing these firearms.
A Firearm Examiner must be able to describe to a jury how a particular firearm
functions and why a particular firearm may have malfunctioned. This skill
is learned through extensive training in the section, by touring firearm manufacturing
facilities and by attending armorer courses sponsored by various firearm manufacturers.
A new tool being used by the Firearm Examiners in the Section is the Integrated BallisticsIdentification System (IBIS). IBIS is a computer based system for analyzing and correlating specially produced bullet and cartridge case specimen photographs that have been entered in databases. The purpose of IBIS is to link evidence bullets and cartridges cases recovered at crime scenes where no firearm has been found or submitted to firearms received in other cases or to evidence in other cases. The Firearm Examiner still bears the responsibility of making the final determination on identifications but IBIS provides the possibility of linking firearms to evidence or evidence to evidence in a way that was not ever possible.
For more information on Firearms Identification, Tool Mark Identification, Firearm Function, Gunshot Residue Distance Determinations, and other related topics read the following books and/or articles:
Matthews, J. Howard (1962), Firearms Identification, Volume I., University of Wisconsin Press, Library of Congress Catalog Card Number 62-14411.
Hatcher, Jury and Weller (1957), Firearms Investigation, Identification and Evidence, Stackpole Books.
Moenssens, Moses and Inbau (1973), Scientific Evidence in Criminal Cases, Chapter 4: 111-169, The Foundation Press, Inc.
Davis, John E.(1958), An Introduction to Tool Marks, Firearms and the Striagraph, Charles C. Thomas-Publisher, Library of Congress Card Catalog Number - 57-12543.
The Association of Firearm and Tool Mark Examiners (AFTE) Journal, Published quarterly since 1969 by AFTE. Editor - Jerry Miller, Atlanta Forensic Science Laboratory, 2600 Century Parkway, NE, Suite 410, Atlanta, Ga. 30345.
The following is a bibliography of articles published by Examiners in the Firearm and Tool Mark Section:
- Bishop, Eugene, " Tool Mark Identification on Nails", AFTE Journal, Volume 27, Number 4, October 1995, pages 306 - 309.
- Bishop, Eugene, " Tool Mark Identification on a Black Powder Revolver", AFTE Journal, Volume 27, Number 4, October 1995, pages 310 - 313.
- Goodman, R. Eric, Santora, David N., Trochum, Tom, " The Kahr K9", AFTE Journal, Volume 28, Number 3, July 1996, pages 166 -167.