AFTE Store - Impacts of Submersion DNA Extraction on Examination of Cartridge Cases

Following research studies on the effectiveness of extracting touch DNA from cartridge cases by submerging them in an extraction buffer (i.e. “dunking”), this study seeks to determine the potential detrimental effects that this process may induce prior to microscopic examination. Multiple studies have been done on this topic from the perspective of forensic biologists, focusing on quality and quantity of DNA extracted and profiles obtained; however, these studies have been lacking any interdisciplinary analysis regarding whether the cartridge cases processed in this way maintain their probative value for microscopic analysis. This pilot study attempts to answer whether the consequences to the individual marks used for identification in firearms examination are so severe that the method should not be pursued at all, or whether limitations should be placed on the procedures used. This research currently involves two rounds of testing, exploring as many variables as feasible, including caliber, metallic composition of cartridge case and primer, type of extraction buffer used, time for which the cartridge cases are incubated, post-dunking cleaning, and packaging. The overall goals of the study are to increase the firearm examiner’s awareness of the practice, and use observations to guide policies for laboratories performing these tests.