| Porcine tissue samples shot with two different types of bullets, jacketed and non-jacketed, were collected in the fresh state and throughout moderate decomposition. Wound samples were microwave digested and analyzed using inductively coupled plasma mass spectrometry (ICP-MS) to detect all elements present in gunshot residue (GSR). Elements detected included antimony (Sb), barium (Ba), and lead (Pb), which are considered characteristic of GSR, as well as iron (Fe) and copper (Cu). These five elements were used to differentiate shot tissue and unshot tissue, as well as tissue shot by the two different bullet types, in both the fresh state and throughout moderate decomposition. The concentrations of Cu, Sb, and Pb were able to distinguish between the two bullet types in fresh tissue samples at the 95% confidence level. Copper and Pb were able to differentiate the bullet types throughout moderate decomposition at the 99% confidence level. The source of these distinguishing elements is likely the different bullets. A sampling study carried out on a fresh non-jacketed bullet wound determined that the optimal sampling position to detect all elements considered characteristic of GSR using ICP-MS is directly adjacent to the wound and as far out as two centimeters from the entrance wound in any direction. |
