Firearms and Toolmarks - Ohio Attorney General Dave Yost

Firearms Unit

The manufacturing process uniquely marks firearms, meaning that individual guns can leave distinct marks on any bullets and cartridges fired from them. These marks make it possible to link such evidence back to the originating weapon.

Scientists in the Firearms Unit conduct ballistics examinations to tie ammunition and related components to particular firearms. For example, many valuable items manufactured today, including firearms, have serial numbers die-stamped for identification. When serial numbers are removed and/or obliterated, forensic scientists in the Firearms Unit can utilize a variety of techniques to restore the original serial number.

FAQsProcedures & Accreditation

What does a firearms examiner do?
A: A firearms examiner’s primary duties include testing all types of firearms to determine whether they function properly and whether fired ammunition components, such as cartridge cases and bullets, came from a particular firearm.
What is forensic firearm identification?
A: The forensic firearm discipline primarily is concerned with determining whether a bullet, cartridge case or other ammunition component was fired by a particular firearm.
How is fired ammunition linked to a specific firearm?
A: Firearms examiners use a comparison microscope, an instrument that allows examiners to view and compare two pieces of evidence side-by-side and magnified. For example, the two items could be a bullet found at a crime scene and a bullet the examiner test-fired from the firearm in question. Examiners analyze characteristics of the evidence — such as whether marks left on each bullet match — to conclude whether the items have a common origin.
Is it really possible to match a bullet or cartridge case to a particular gun, knowing that a gun manufacturer may produce thousands of identical firearms?
A: Yes. During the manufacturing process, unique characteristics are imparted onto a firearm. When a cartridge is fired, these unique characteristics can be transferred onto the fired cartridge case and fired bullet. These transferred characteristics — they might be too tiny for the human eye to see — can be identified using a microscope.
Is it possible to determine when a firearm was last fired?
A: No.
What kind of results can be expected from a firearms examination?
A: There are five conclusions that firearms examiners can reach in their analysis:
- Source identification
- Support for the same source
- An inconclusive result
- Support for a different source
- Source exclusion
Find more details in this conclusion scale document.
What are the limitations of the analysis?
A: The condition of the evidence typically is the biggest limitation in firearms analysis. If a piece of evidence is too badly damaged, a comparison may not be possible.
What is NIBIN?
A: NIBIN is the National Integrated Ballistic Information Network, a computer-assisted ballistics imaging database used by firearms examiners to compare images of the unique markings registered on cartridge cases after a weapon is fired. The primary goal of NIBIN is to link cases that are unsolved or previously unassociated. At BCI, this work is completed at the Richfield Laboratory. Read here about why all law enforcement agencies should use NIBIN.

Database notes

A database of serial numbers from guns reported stolen in Ohio, which is operated by the Attorney General’s Office, can be found at this link.

BCI takes part in the National Integrated Ballistics Information Network (NIBIN), a computer-assisted ballistics imaging system that stores and compares images of the unique markings made on fired cartridge cases. NIBIN is also useful in linking crimes previously thought to be unrelated.

Unit Contacts

Mark Losko
London Laboratory
Laboratory Supervisor
740-845-2523 | Mark.Losko@OhioAGO.gov

Cassandra Agosti
Bowling Green Laboratory
Laboratory Supervisor
419-419-3572 | Cassandra.Agosti@OhioAGO.gov

Barabara Hoover
Richfield Laboratory
Laboratory Supervisor
234-400-3683 | Barbara.Hoover@OhioAGO.gov

Firearms Unit

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