Investigation of gunshot residue patterns using milli-XRF-techniques: first experiences in casework

Rüdiger Schumacher; Martin Barth; Dieter Neimke; Ludwig Niewöhner

doi:10.1117/12.853852

3 June 2010 Investigation of gunshot residue patterns using milli-XRF-techniques: first experiences in casework

Rüdiger Schumacher, Martin Barth, Dieter Neimke, Ludwig Niewöhner

Proceedings Volume 7729, Scanning Microscopy 2010; 772917 (2010) https://doi.org/10.1117/12.853852
Event: Scanning Microscopy 2010, 2010, Monterey, California, United States

Abstract

The investigation of gunshot residue (GSR) patterns for shooting range estimation is usually based on visualizing the lead, copper, or nitrocellulose distributions on targets like fabric or adhesive tape by chemographic color tests. The method usually provides good results but has its drawbacks when it comes to the examination of ammunition containing lead-free primers or bloody clothing. A milli-X-ray fluorescence (m-XRF) spectrometer with a large motorized stage can help to circumvent these problems allowing the acquisition of XRF mappings of relatively large areas (up to 20 x 20 cm) in millimeter resolution within reasonable time (2-10 hours) for almost all elements. First experiences in GSR casework at the Forensic Science Institute of the Bundeskriminalamt (BKA) have shown, that m-XRF is a useful supplementation for conventional methods in shooting ranges estimation, which helps if there are problems in transferring a GSR pattern to secondary targets (e.g. bloody or stained garments) or if there is no suitable color test available for the element of interest. The resulting elemental distributions are a good estimate for the shooting range and can be evaluated by calculating radial distributions or integrated count rates of irregular shaped regions like pieces of human skin which are too small to be investigated with a conventional WD-XRF spectrometer. Beside a mapping mode the milli-XRF offers also point and line scan modes which can also be utilized in gunshot crime investigations as a quick survey tool to identify bullet holes based on the elements present in the wipe ring.

Citation Download Citation

Rüdiger Schumacher, Martin Barth, Dieter Neimke, and Ludwig Niewöhner "Investigation of gunshot residue patterns using milli-XRF-techniques: first experiences in casework", Proc. SPIE 7729, Scanning Microscopy 2010, 772917 (3 June 2010); https://doi.org/10.1117/12.853852

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