Firearms

Firearms examination is a discipline of forensic science which has as its primary concern to determine if a cartridge case, bullet or other ammunition component was fired in a specific firearm. This is actually a form of toolmark examination where the firearm, because it is made of material harder than the ammunition components, acts as a tool to leave impressed or striated marks on the various ammunition components that come into contact with the firearm. The Firearms section routinely performs functionality evaluations on submitted firearms, evaluations of fired evidence to include, microscopic examinations and comparisons, as well as serial number restorations on firearms.

Submitted firearms are evaluated to determine proper function under laboratory conditions. When safe to do so, the firearms are test fired and the bullets and cartridge cases are collected. This provides the examiner with exemplars from the firearm that may be compared to other evidence items.

When fired evidence is submitted to the laboratory, the evidence will be examined to provide information to the submitting agency. For instance, caliber determination of fired bullet and cartridge case evidence as well as a list of possible firearms that could have fired the evidence can be provided. Microscopic examination of fired evidence will be performed in an attempt to determine if any common sources exist or to identify/eliminate questioned firearms when submitted.

Firearms may be submitted when an attempt has been made to obliterate the serial number. Serial number restoration will be performed by utilizing mechanical and chemical methods, which may result in the restoration of a partial or complete serial number.

Gunshot residue and distance determination is the examination of clothing and other items for the presence of gunshot residue or shot patterns in an attempt to determine muzzle-to-object distance. Although these examinations are not conducted at the Jefferson County Regional Crime Laboratory, it is important that submitting agencies be aware of the potential forensic information that may be gained through these examinations. The Laboratory’s Firearms Examiners are happy to assist with the pursuit of any additional examinations which may be of forensic benefit to a criminal case.