Bullet contribution to inorganic residue on targets

Abstract

Identifying the composition and the physical characteristics of the bullet that generated a specific hole in the victim's clothes or skin may be crucial in shooting incident reconstructions. In forensics, chemographic tests are routinely conducted to visualize lead, copper, or nitrite deposits around entrance holes with the aim of confirming a projectile impact or estimating the shooting distance. A quantitative chemical analysis of the particles collected from the periphery of an entrance hole is required for identifying the type of passing bullet. In real cases, such analysis would be affected by the possible cross-contributions of both inorganic residue from the discharged ammunition primer and metallic fragments from previous rounds projected from the gun barrel. The actual contribution of the sole bullet to the composition of the inorganic residue deposited on target is then hardly distinguishable. In the present study, the deposits left by three different copper/zinc jacketed bullets on targets were analysed by inductively coupled plasma optical emission spectrometry and by X-ray fluorescence spectrometry. To reduce any possible source of contamination, a heavy metal free primer mixture and a brand new pistol were used. Elements of interest were quantified varying the shooting distances with the aim of identifying different bullet contributions to the inorganic residue on targets.

Keywords

• Forensic sciences
• Bullet holes
• Inorganic GSR
• ICP-OES
• XRF
• Cotton targets