FIB - dual platform instrument : an investigative tool to distinguish between gunshot residue and environmental particles

Forensic science plays an important role in the investigation of firearm related crimes. It can establish an association between firearms and assailant by detecting and identifying gunshot residue particles (GSR)- solid microscopic particles ejected from the openings, gaps and clefts of firearn1s. These particles are condensed from the high temperature and high pressure gases produced by the deflagration of the primer and propellant in the cartridge case positioned in the breech of the weapon. These particles are frozen by rapid cooling and are deposited on the body and clothing of the shooter and on nearby surfaces. If the rate of cooling is sufficiently high the solid particle should retain the structural disorder of the liquid-a feature anticipated in GSR morphology. The physical appearance of the particle may be described as a morphology that indicates rapid solidification from a molten state. The particles are detected and identified by particle analysis using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) spectroscopy.