Effects of the interaction of gunshot residue plume and cotton fabrics—an empirical study towards extensive assessment of close-range shooting distance

Abstract

Shooting distance assessment is a substantial problem in forensic investigation of suicides and homicides committed by means of a firearm. There are cases when the gun or ammunition used in a crime or both are not available for forensic testing and so reference shooting patterns cannot be obtained for shooting distance assessment with chemographic methods. In such cases, the shooting distance evaluation has to rely solely on the evidence of gunshot wounds in human tissues and clothing. To facilitate a robust assessment of the shooting distance in such circumstances, the effects of contact and close-range shooting using a 9 mm Luger pistol and traditional types of ammunition on different popular types of cotton textiles were examined. This study is focused not only on the distribution of gunshot residue but also on changes undergoing within the textiles. Both chemical and morphological examinations of the deposited gunshot residue and characterisation of the changes in the fibres of the selected textiles were performed by means of optical microscopy, scanning electron microscopy and energy dispersive X-ray spectrometry as well as infrared spectrometry. It was established that not only the appearance of the shooting pattern but also the distribution of gunshot residue, being collected from the perimeter of 5 cm around the gunshot hole, depends on the properties of the textiles, i.e. their type, structure, density and thickness. In addition, it was found that on the surface of changed fibres, being collected from the edges of contact and near-contact shots, there were present numerous spherical inorganic residues of diameters usually much smaller than 1 micrometre.