Comparative evaluation of gunshot residue collection techniques: A preliminary study

The collection and evaluation of GSR distributed in a firearm-related scene is crucial in the resolution of most crime cases involving firearm. The study was conducted in an indoor firing range (Ballistic Research Centre and Testing Range) with a controlled room temperature and humidity of 30°C and 56% respectively. Firing was performed using three different long range firearms; AK-47 rifle (7.62 × 39mm calibre), Self-Loading Rifle-SLR (7.62 × 51mm calibre) and Carbine rifle (9 × 19mm calibre). Atotal of 60 rounds comprising 20 shots each from AK-47, SLR and 9mm Carbine rifle were performed. Samples were further subjected to qualitative and quantitative examination using Energy Dispersive X-Ray Florescence (EDXRF-7000, Shimadzu) and Mass Spectroscopy. The results of the study analysis indicated that, the best collection technique that may enhance quantification of enough GSR deposit was in the order of; barrel was > hand swab> GSR at an angle of 90°> GSR at an angle of 45°. The simultaneous presence of Pb, Ba, and Sb which serves as a requirement to fix the identity of GSR is most likely to be sufficiently detected in GSR samples collected through barrel wash relative to hand swab of the shooter.