Gunshot Residue (GSR)Particle
Analysis (cont)Gunshot Residue (GSR)Particle
Analysis (cont)...combination of chemical elements not found in the environment nor produced by any industrial processes. Examples of unique GSR particles are those that contain lead (Pb), antimony (Sb) and barium (Ba) or only antimony and barium. In addition, to the unique GSR particles, gunshot residue also contains particles with chemical compositions that are consistent with GSR but not unique. These particle types can be produced by processes other than firing a gun. Consistent GSR particles contain lead, antimony or barium or some combination of these elements.
GSR particles are collected using a special adhesive tape. Samples may be taken from a suspect's hands or clothing or from surfaces near the suspected gunshot. The tape lift sample is examined using a scanning electron microscope equipped for x-ray microanalysis. GSR particles can be easily seen using backscattered electron imaging in the SEM. and GSR particles as small as 0.5 micrometers can be identified.
|
An Asian-American restaurant owner was driving home one evening when a car full of teenagers cut him off at an intersection. Words were exchanged at the next stoplight. The kids continued on dropping their friends off at their homes. Unbeknownst to the teenagers, the restaurant owner had dropped back a distance, turned off his lights and was following them. The teens' car stopped in front of one of the kids homes. The restaurant owner pulled up behind them and shot one of the teenagers just when he was about to enter his house. The shooters' car sped away. Police later arrested the restaurant owner. His car had been stored in a relatives garage since the shooting. One important question that the police needed answered was had the shot been fired from inside the restaurant owner's car. The police believed the shot was fired through the open front passenger side window. GSR samples were taken from the passenger's seat and back-rest,dashboard and glove compartment door. Gunshot residue was found on the back-rest and the dashboard and some was found on the seat but very little GSR was found on the glove compartment door. This evidence indicated that the shot was fired from inside the car. The reason that only a small amount of GSR was found on the glove compartment door was that the door was up when the gun was fired. The suspect had kept his gun in the glove compartment. |
|
|
| Matricardi, V. R. and Kilty J. W., Detection of Gunshot Residue Particles from the Hands of a Shooter, J. of Forensic Sci., 22, 725-738, 1977. |
| Wolten, G. M., Nesbitt, R. S., Callowasy, A. R., Loper, G. L. and Jones, P. F., Particle Analysis for the Detection of Gunshot Residue: 1. Scanning Electron Microscopy/Energy Dispersive X-ray Characterization of Hand Deposits from Firing, J. of Forensic Sci., 24, 409-422, 1979. |
| Basu, S., Formation of Gunshot Residues, J. of Forensic Sci., 27, 72-91, 1982. |
| Germani, M. S., Evaluation of Instrumental Parameters for Automated Scanning Electron Microscopy/Gunshot Residue Particle Analysis, J. of Forensic Sci., 36, 331-342, 1991. |