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Evaluation and Optimization of DNA Recovery and Amplification From Bullet Cartridge Cases

NCJ Number
Date Published
March 2019
47 pages
Findings and methodology are reported for a research project with the goal of optimizing the recovery, extraction, and amplification of trace DNA from a variety of commonly encountered cartridge case types.

Both existing and novel methods for the recovery and extraction of DNA from metal cartridge cases were assessed in developing robust protocols and an optimized workflow. The applicability of the optimized workflow was demonstrated over a wide range of commonly encountered ammunition calibers and cartridge case types. Standard operating procedures were written to facilitate adoption by caseworkers. Optimized recovery and extraction methodologies are described. For unfired cartridges, the soak and sonicate method consistently generated the highest DNA yield and profile quality regardless of metal type. Tape lifts generated the second highest yield except with steel cartridge cases. Regarding DNA extraction, the use of the organic extraction method consistently produced the best results for all metal substrates. Thus, sufficient quantities of DNA can transfer from a handler during the manual loading of a magazine to support the generation of interpretable DNA profiles from unfired rounds. Using a soak and sonicate recovery method paired with organic extraction, the average total DNA yield ranges from 430-930pg. Interpretable profiles were subsequently obtained for just over 95 percent of cartridge cases, regardless of the metal composition. The DNA recovery and extraction results obtained with fired cartridges followed the same pattern as unfired cartridges; however, fired cartridges were associated with significantly lower DNA recovery yields and lower profile quality. Possible reasons for the difference in DNA recovery yields from fired and unfired cartridges are discussed. 21 figures and a listing of disseminations from the project

Date Published: March 1, 2019