Analysis of gunshot residue deposited on cotton cloth target at close range shooting distances

Abstract

The study of gunshot residue (GSR) has become imperative in forensic firearm examination. It may be used to estimate firing distance, to identify bullet holes and to determine whether or not a person has discharged a firearm. This study emphasized on the ex amination of the pattern of GSR particles deposited on cotton cloth target at different shooting distances (3 inch-12 inch). Two types of pistol (semiautomatic and revolver) and ammunitions (Syarikat Malaysia Explosive (SME) and Winchester) were used for the shooting test. All shooting tests were performed at Lapang Sasar of Pasukan Gerakan Am PDRM, Cheras. The results showed that GSR particles produced on cotton cloth by semiautomatic pistol using SME 9 mm ammunition generated higher amount and larger GSR particles which were almost completely burnt particles. The nitrite residues were confirmed using modified Griess test that revealed semiautomatic pistol produced considerable amount of nitrite residues. Scanning Electron Microscope (SEM) micrograph of GSR particles discharged from semiautomatic pistol using SME 9 mm ammunition revealed a mean particle size of 2.6 µm with spherical shapes. On the other hand, using revolver pistol with SME 0.38 Special ammunition, the GSR particles produced were small in amount. The modified Griess test also revealed that revolver pistol generated tiny amount of nitrite residues. Nevertheless, using Winchester 0.38 Special ammunition, the GSR particles discharge were of high amount and large in size which composed of completely unburned, partially burnt and completely burnt particles. Whereas SEM micrograph of GSR particles discharged from revolver pistol using Winchester 0.38 Special ammunition generated irregula r cluster grain with a mean diameter of 3.3 µm. Sodium rhodizonate test was successfully applie d for detecting the presence of lead residues around the bullet hole for both pistols.