Investigating airborne GSR particles by the application of impactor technology

Gunshot residues (GSR) are of interest when firearms are used in criminal cases. GSR analyses are usually based upon the elemental composition and morphological appearance of very minute particles by means of SEM-EDS. Based on these two parameters, GSR particles are divided into specified classes. The amount of detected GSR particles depends on the time since discharge of the weapon and the sampling position relative to the location of discharge. In this paper, the influence of time on the local concentration and the distribution of airborne GSR particles were investigated with impactor technology. The particle concentration is constant in the still room; changes in concentration are only related to the emission of GSR particles by the discharge of a firearm. Here we showed that large quantities (50% of max. concentration) of airborne GSR particles can be detected several hours after discharge and contamination can take place as much as three hours after discharge. This study is a first approach to describe the propagation and sedimentation of GSR particles. With respect to statistical confirmation further experiments are already projected in order to comprehend the well-known variability of GSR emission and behavior. (C) 2018 Elsevier B.V.