Linking of Shooter and Shooting: Detection of Gunshot Residue on Shooter's Hands Using Microscopy and Scanning Electron Microscope-Energy Dispersive X-Ray Methods

One important link in the chain of proof during investigation of shooting cases is the evidence to prove a person had fired a firearm, or somehow was connected with the firing activity. Gunshot residues (GSR), particularly on shooter's hand, could provide significant aid in such investigation. Therefore, this study was aimed to investigate the detection of GSR particles recovered from the hands of shooter using two sampling methods, namely stubbing and swabbing, on the basis of the types of firearms and ammunitions, as well as the varying sampling sites. By considering lead, barium and antimony as the criterion to definitely confirm the presence of GSR, the experimental results revealed that greater number of GSR particles were shown in those samples subjected to firing by using revolver with .38 SPL ammunition compared to semi-automatic pistol with 9 mm ammunition (p = 0.034). Based on Kruskal-Wallis test, there was no statistically significant association shown between the sampling sites and number of GSR particles detected (p= 0.545 for semi-automatic pistol; p = 0.218 for revolver). All stub samples demonstrated positive detection of GSR particles, but only one single characteristic GSR particle was detected on swab samples. Further examination on the collection efficiency of respective sampling methods demonstrated with no significant association between the types of firearms and number of GSR particles detected from the respective cartridge cases (p = 0.568). The number of swabbing from spent cartridge case gave almost similar testing result (p = 0.561). This study has successfully detected the presence of GSR particles, which could serve as a supporting evidence to relate a suspect to a shooting case. Although swabbing has limited ability in recovering GSR samples from the hands of shooter, it is useful whenever a stub is not available or to recover GSR particle from a place where could not be reached by a stub to avoid the loss of trace particles. (author)