Evaluation of the possibility of differentiation between various types of ammunition by means of GSR examination with SEM–EDX method

Abstract

Gunshot residues originating from six types of pistol ammunition were studied. Six persons who normally have no contact with weapons fired three times, each person from a different pistol. Samples of gunshot residues were collected from the shooters’ hands using aluminium stubs with black carbon adhesive tabs and subjected to examinations of their morphology and elemental content by means of a scanning electron microscope with an energy dispersive X-ray spectrometer in an automatic manner. In a comparative study of the samples, only primer residues were taken into account. The frequency of occurrence of particles representing a certain chemical class against the total number of detected particles was expressed as a percentage. Mutual relations between the frequencies of occurrence of the residues of particular chemical content were found to be different for most of the studied ammunition types using a non-statistical approach — and by means of non-parametric statistical methods ( R-Spearman and τ-Kendall correlation coefficients), it was possible to differentiate one ammunition type from each of the other ammunition types examined. The performed examinations have revealed some differences in the frequencies of occurrence of certain chemical classes of primer residues, observed for various types of ammunition. These differences could constitute a valuable contribution to group identifications of ammunition made on the basis of physical and chemical examinations of gunshot residues.