Gunshot residue analysis (GSR) is extensively used around the world for determining if a person has discharged a firearm. GSR particles are solid microscopic particles ejected from the openings, gaps and clefts of firearms. 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 deposited on the body and clothing of the shooter as well as on nearby surfaces. GSR particles are identified by two features, composition and morphology. The presence of lead, antimony and barium in a particle is considered characteristic of firearms origin.
The traditional SEM systems used for GSR analysis are usually expensive instruments that take-up large laboratory areas, involve extensive training of the users, and even to some extent difficult to operate. Over the last couple years, there has been a growing market for benchtop SEM’s mainly due the requirements and demands of the users. Bench top SEM’s are becoming more popular due to 1) ease of operation, 2) less laboratory requirements, 3) portable and easy to setup and 4) affordability with less maintenance cost. The users are finding these benchtop SEM’s very user friendly due to the ease of use and limited training required for basic SEM imaging.
There have been some major improvements in the benchtop SEM design and capabilities with the addition of microanalysis systems, which has been very beneficial in forensic applications. More recently, an automated gunshot residue system (GSR) system has been interfaced between the Phenom SEM (with automated stage) and the Amptek silicon drift detectors (SDD’s). This presentation will show results collected from the automated benchtop SEM-GSR system as well as the system being utilised for particle searching in other applications.