Firing distance estimation based on the analysis of GSR distribution on the target surface using ICP-MS—An experimental study with a 7.65 mm × 17 mm Browning pistol (.32 ACP)

Abstract

An experimental study aiming to estimate the firing distance was conducted using a 7.65mm×17mm Browning (.32ACP) pistol. Briefly, test shots were made against a target of cotton tissue (35cm×35cm), and the amounts of antimony (Sb), barium (Ba), and lead (Pb) deposited in quadrangular pieces (1cm×1cm) of the target cut from four radial positions at increasing distances from the bullet entrance hole (“samples”) were determined by inductively coupled plasma-mass spectrometry (ICP-MS).The data obtained were used to search for a mathematical model for estimating the firing distance. The best model was a simple linear correlation between FD (the firing distance) and ln c (where c is the content of Sb, Ba or Pb in the samples, expressed in μg/g of target tissue).Best results were obtained with samples collected at radial distances within 2.0–3.0cm from the bullet entrance hole. Using this approach, it was possible to accurately (±6cm) estimate the firing distance in the interval [20–90] cm from the target.