A study of dispersion of gunshot residue from a frequently used Serbian ammunition cal. 7.65 mm to support selected aspects of casework in North Macedonia

The subject of this research was the inorganic gunshot residue component collected from shooting patterns obtained on woven cotton cloth using a Pietro Beretta model 70 pistol, cal. 7.65 mm and Serbian ammunition for the following muzzle-to-target distances: 25, 50, 75, 100 and 125 cm. For each distance, three rounds of shooting were performed. Particles were lifted within a 10 cm radius of the projectile entrance and automatically analyzed using a scanning electron microscope coupled with an energy dispersion X-ray spectrometry. The obtained data on the populations of particles were analyzed taking into account their numbers, chemical classes and sizes. The results showed an apparent maximum incidence within all particles containing barium at about 50 cm distance. Also, lead particles revealed a distinct behaviour, being dominant at a 25 cm distance, falling below the other chemical classes, and finally becoming dominant again at 125 cm. The analysis of the frequency of occurrence of particles sorted according to their sizes confirmed that the small particle population is the largest, and their distribution in function of the equivalent circle diameter is exponential-like. The obtained results provided knowledge on the distribution of particles in the vicinity of the tested firearm and ammunition cal. 7.65 mm which generally corroborates with similarly studied GSR distributions obtained for the use of pistols cal. 9 mm. This information, together with the examinations of gunshot damages and other types of residues such as soot or unburned propellant grains may support qualitative inferences on shooting distance estimation, especially in cases, when the firearm and cartridges are not available to perform test shooting. In such cases even roughly estimated shooting distance can be helpful, e.g. for confirming or excluding the possibility of self-inflicted injuries or suicide and infer on the mutual position of the shooting stage actors. An example of casework that illustrates intermediate shooting distance estimation is presented.

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

This study is focused on the distribution of gunshot residue as well as changes in the textiles to support forensic investigations of suicides and homicides committed by means of a firearm.

Chemical and morphological study of gunshot residue persisting on the shooter by means of scanning electron microscopy and energy dispersive X-ray spectrometry

Persistence of gunshot residue (GSR) simultaneously collected from hands, face and hair, and clothing of the shooting person was examined. Samples were collected from five shooters in nine time intervals after a single shoot with a Luger 9 mm pistol, in the range of 0-4 h and examined with scanning electron microscopy and energy dispersive X-ray spectrometry. Numbers of particles, frequencies of occurrence of certain compositions of particles, and their sizes in function of the time intervals were inspected. The greatest numbers of particles were observed in samples collected from hands right after shooting, but they decrease quickly with time. In samples collected from the face smaller initial numbers of particles were found, but they lasted at a similar level longer. The estimated half-life times of particles were less than 1 h for samples taken from the hands, over 1 h for clothing and about 2-3 h for the face. In samples collected at longer intervals after shooting, there were particles present of small sizes and irregular shapes. The results demonstrate that including evidence collected from the suspect's face and hair may increase the probability of detection of GSR in cases when the suspect has not been apprehended immediately after the investigated incident.