Detection of Gunshot Residue in Blowfly Larvae and Decomposing Porcine Tissue Using Inductively Coupled Plasma Mass Spectrometry (ICP‐MS)*

Abstract

Blowfly larvae and porcine tissue contaminated with gunshot residue (GSR) were collected during summer and winter months, over a 37-day and a 60-day sampling period, respectively. Wound samples were microwave-digested and analyzed by inductively coupled plasma mass spectrometry (ICP-MS) for the detection of antimony, barium, and lead. During summer, the 37-day sampling period encompassed all stages of decomposition, except skeletonization. The three elements were detected in larvae only on days 3 and 4 after death but were detected at significant levels in tissue samples throughout the entire sampling period. In winter, no significant decomposition was observed throughout the 60-day sampling. Although temperatures were too low for blowfly activity, the three elements were detected in the tissue samples at relatively constant, significant levels. Hence, GSR determination in tissue was more dependent on decomposition stage rather than time since death.

Trace metal analysis by laser ablation-inductively coupled plasmamass spectrometry and x-ray K-edge densitometry of forensic samples

“…sharp force, blunt force, or projectile trauma, is important in forensic investigations to establish the cause of death. Projectile trauma can be difficult to distinguish from sharp force trauma on a decomposing carcass due to the stage of decomposition and insect activity around and within the wound tracts, (63,64) especially if the bullet is not recovered at the scene.…”

“…Depending on the type of environment in which the body is exposed, the insect activity on the remains, and the stage of decomposition, GSR is only detectable by SEM-EDS around the entrance wound for a short period of time (~24 hours) (63). Efficient GSR collection may be hindered by liquids and adipocere that may be present on the surface of decomposing remains (63).…”

“…Only a few radiochemical and microscopic studies have been conducted regarding the analysis of gunshot wounds in decomposing remains (63,65,66,67).…”

“…Therefore, organisms, such as fly larvae, that feed around wounds on decomposing tissue have been studied (63,64,65). ICP-MS was also used to analyze GSR on skin tissue around gunshot wounds on a pig carcass to distinguish projectile from sharp force trauma in later stages of decomposition (63).…”

“…ICP-MS was also used to analyze GSR on skin tissue around gunshot wounds on a pig carcass to distinguish projectile from sharp force trauma in later stages of decomposition (63). Elements consistent with gunshot residue were present at higher concentrations in the skin tissue around the gunshot wounds compared to the tissue around the stab wounds for 37 days after death in the summer and 60 days after death in the winter study (63). Udey et al (69) further studied the GSR in tissue by examining the possibility of differentiating bullet types in fresh and decomposed tissue using ICP-MS. All of these studies were conducted using dissolved samples.…”