FIREARM and TOOLMARK LABORATORY

The Firearms/Toolmark section is responsible for documenting, examining and comparing any evidence related to firearms or tools.  Using comparison microscopy, two objects are simultaneously compared to each other to determine if the toolmarks observed on them originated from the same source.  Firearm examination includes functionality testing, demonstration of operability, microscopic comparison, serial number restoration, and muzzle-to-target examinations.  Toolmark analysis includes the examination of any tool and/or toolmark.  Examples of tools are bolt cutters, screwdrivers, or knives; while toolmarks can be from any object that a tool can impart marks to, such as padlocks, cartilage, or wires.  If an object is broken into pieces, a fracture match examination can be conducted to determine if the two pieces were formerly a single unit.

 

Muzzle-to-target or distance determination is the examination and/or chemical processing of clothing for the presence of gunshot residues that are predominantly expelled from the muzzle.  This type of examination is to determine how far the muzzle of the firearm was from the target at the time of discharge.  There are many variables involved with distance determination examinations (such as barrel length, caliber, type of ammunition and distance); in order for TCME firearms examiners to conduct a distance determination examination, the following should be submitted for examinatoin:

  • Suspected firearm used in the incident 
  • Ammunition used in the incident 
  • The fired cartridge case(s) and/or fired bullet(s) from the incident
  • The articles of clothing associated with a gunshot, e.g., if the victim was shot in the chest, we do not need the underwear, pants, socks or shoes. 
  • Crime scene photos
  • Autopsy report and photos 

 

 

Firearm/Toolmark Procedures