Firearms & Toolmarks Chapter 9

Toolmark Scratch or other marking left by the action of a tool on an object Firearm identification Breaking and entering doors and windows Impression on the edge of a cut wire

Firearms Identification Forensic ballistics Firearms examinations (study of projectiles in motion) Wound ballistics Gunshot residue Serial number restorations Estimate distance gun was shot

Firearms Pistols/handguns (revolvers and self-loading) Rifles Machine guns Submachine guns Shotguns All firearms except shotguns use bullets that can be compared based on rifling patterns (grooves/striations)

Firearm Evidence Trace evidence collected first from the surface of the weapon Bullet and cartridge comparisons performed by matching striations (rifling) Bullet caliber also determined Striations may not always match if gun is rusted Trace evidence: Fingerprints, gunshot residue, fibers, hairs

Firearm Evidence Continued… Gunshot residue pattern Distance shot- no residue left on victim (greater than 18 inches away) Close range- residue left on victim Contact shot- muzzle of gun in contact with victim

Distance shots have bullet holes with rounded edges Distance does not impact size of bullet hole Close range shots cause stippling patterns on victim Shotgun shots Gun shot pattern increases with distance

Other toolmarks… Matched by creating cast of suspect’s tool to the toolmark at the scene