Development and application of a new nose hairs sample collection device for GSR Particles by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS)

Abstract

When a firearm is discharged, a gaseous cloud containing characteristic particles of gunshot residue (GSR) are released forward and behind at high speed, depositing on clothing, hands, face and hair, as well as being inhaled and therefore retained in the nostrils of the person who fired the weapon. GSRs have characteristic sizes and morphologies and consist of a combination of lead, antimony and barium, as well as other elements. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) is a widely accepted technique for the analysis of these residues; however, little has been reported on samples taken from the nostrils of the suspect that discharged the shot. The analysis of residues found on hands has been more frequent. This article presents a device (Nasal Stub) developed by us for the non-invasive collection of GSR particles from the nostrils and a platform also developed by us to contain these devices that is compatible with SEM-EDS. To evaluate the effectiveness of our Nasal Stub to collect GSR particles from nose hairs, four types of firearms of different calibers were utilized. Nasal samples were collected at 0, 2, 4, 6, 8, and 20h after firing. The results show that the nasal device was able to recover GSR particles from nose hairs for all the weapons used, even, in some cases, over 20h after firing. It was concluded that Nasal Stub and its methodology proposed for the analysis of nasal GSR from nose hairs by SEM-EDS was effective and that it can complement other traditional analyses of GSR particles, increasing the amount of evidentiary support for the forensic analysis presented in a tribunal or court.