Since the introduction of scanning electron

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Since the introduction of scanning electron microscopy/energy dispersive X-ray examination of gunshot residue in the 1970s, it has been considered that the firing of a gun produces materials that are unique to that process. Wolten [718], in the most comprehensive study of GSR analysis by SEM, stated that micron-sized particles, having a morphology consistent with rapid cooling, formed a liquid state. They contained the elemental combustion of either lead/barium/antimony or barium/antimony and were unique to the detonation of the primer of a round of ammunition. Metallic particle classification was carried out in the following way: the most characteristic (unique) particles were singled out, followed by indica- tive, one and two component particles, e.g. antimony, lead, lead/antimony, always accompanying the former and occurring in considerably greater quan- tities. [721]. Finding GSR on material received from a suspect confirms his or her participation in the event. Only a few experienced specialists undertake the difficult task of identify- ing used ammunition on the basis of qualitative assessment of differences in the chemical composition of GSR [712]. Recently, some attempts were made at a systematic study of primer discharge residue originating from various brands of ammunition. Evaluation of the obtained analytical results was car- ried out by, among other things, chemometric methods [708, 709]. These stud- ies showed significant differences between gunshot residues originating from
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Methodological Developments and Applications 727 ammunition types, and thus it was possible to achieve at least group identifi- cation of ammunition (and hence the type of firearm used) from information on GSR alone. In order to elaborate a reliable scheme of individual classifica- tion of ammunition on the basis of GSR alone, it cannot be excluded that it will be necessary to analyse the internal structure and chemical composition of individual particles [714]. The XRF method, however, is irreplaceable in investigations of gunshot holes occurring on various bases. A fragment of fabric cut from clothing or a fragment of skin or bones together with the gunshot wound can be placed directly in the measuring-dish of the X-ray spectrometer and analysed for the presence of metals originating from the primer, the bullet and the cartridge. Their disclosure confirms the use of a firearm and contributes to inferences about estimations of the shooting distance [716]. Recently, the first attempt to use µ -XRF in examinations of gunshot residues was carried out [710]. Charpentier et al. applied this method to the analysis of gunshot residues from primers of lead-free ammunition and ammu- nition in the area surrounding bullet holes, and found it to be a very important tool for determining shooting distance. They determined the elemental com- position of a 500- µ m zone near the bullet hole. In addition, as the method has a mapping system, it provided data on elemental distribution in a given area.
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  • Spring '14
  • MichaelDudley

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