Library Dissertation Showcase

An investigation into the contamination of firearms teams within Staffordshire Police, and the possibility for transfer of gunshot residue (GSR) between armed and unarmed officers using SEM-EDX analysis

  • Year of Publication:
  • 2020

Concern for potential gunshot residue (GSR) contamination within the police, and concerns regarding the transfer of these residues to crime scenes and suspects, has led to several studies assessing levels at which this contamination might occur. This study aimed to investigate the contamination of officers within the Staffordshire Police Tactical Firearms Unit through their firearms training, and whether this contamination could be transferred to other Staffordshire Police officers within close contact with the firearms unit. Ten 9 mm pistol rounds were fired, and samples were collected from three firearms officers, using Carbon mounted Aluminium stubs. A second group of firearms officers discharged an unknown number of pistol and carbine rounds and were asked to interact with unarmed officers via a handshake. These unarmed officers were then sampled. Particles found on these samples were analysed by Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM-EDX) to determine elemental composition to associate particles with GSR. Elements identified in particles characteristic of GSR included Lead, Barium and Antimony, with further elements of Silicon, Potassium, Aluminium, Sodium and Sulphur also found on samples consistent with GSR. Calcium peaks were prominent in most particles, including those negative for GSR, but these peaks overlapped with Antimony, suggesting they could have been miss identified by EDX spectroscopy. Characteristic GSR particles were confirmed on samples taken directly from shooters, and particles consistent with GSR were found on both shooters and unarmed officers, indicating GSR contamination between police teams can occur. However, these limited particles found could be an underestimate of the GSR levels on officers within Staffordshire Police, and as single particles of GSR cannot be explained as significant, as stated by
the Forensic Science Regulator, the identification of further particles would enhance these results. Thus, it can be said that the probability of transfer occurring within a normal police environment is relatively low.

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