Colorimetric Barium Detection of Gunshot Residues on Cadaveric Human Skin: A Pilot Application for Forensic Purposes

Abstract

In this study we microscopically investigated, for the first time ever, the colorimetric detectability of barium of gunshot residues (GSR) on cadaveric human skin with gunshot wounds. For this purpose we used two different colorimetric techniques known in the literature, namely 0.2% sodium rhodizonate (Na-R-Ba 0.2%) and sodium rhodizonate in alcoholic environment (Na-R-Ba OH 0.2%). At the same time, we have also coupled it with scanning electron microscopy with energy dispersive X-ray (SEM/EDX) analysis and the colorimetric study for the detection of lead of GSR. These techniques were applied to 16 victims who died from gunshot injuries, as well as to a control group. SEM/EDX demonstrated the presence of lead in all cases and barium in 11 of the 16 cases. The subsequent colorimetric technique with Na-R-Ba 0.2% did not show the barium of GSR in any case, unlike the Na-R-Ba OH 0.2% technique. This latter, in fact, has demonstrated the presence of this metal in 2 cases (18%). No microscopic case of false positive was recorded. The evidence obtained with Na-R-Ba OH 0.2% makes this method, applied here for the first time ever, worthy of further study. Meanwhile, although this technique can certainly be applied, it cannot be separated from the contextual colorimetric investigation for lead and the use of more sophisticated techniques.