The effects of soaking for DNA recovery on the striation patterns of fired cartridge cases

ABSTRACT

The recovery of trace DNA from fired cartridge cases has recently gained increased interest throughout the literature, with a variety of methods currently being explored. Soaking fired cartridge cases in a lysis buffer holds potential in producing meaningful DNA profiles; however, chemical interactions between the lysis buffer and brass cartridge cases may limit the efficacy of this method. This preliminary study examines the effects of soaking on the microscopic striation detail of brass and nickel 9 mm Parabellum (9 mmP) calibre and .22 Long Rifle (.22LR) calibre fired cartridge cases. Headstamp and coarse striation patterns on 9 mmP fired cartridge cases and finer striation patterns along the outer wall of .22LR fired cartridge cases were microscopically examined prior to and following soaking. Soaking was performed by submerging the fired cartridge cases in 380 µl of ATL buffer (Qiagen, Germany) for 20 minutes. Microscopic analysis of brass and nickel 9 mmP and .22LR fired cartridge cases showed that coarse and fine striation detail remain unaffected following soaking. These results indicate that comparative ballistics examinations may be performed following DNA recovery using the soaking method.

KEYWORDS:

• Cartridge cases
• touch DNA
• firing effect
• striations

Acknowledgements

The authors would like to thank the NSW Police Force Forensic Ballistics Investigation Section for their support with the collection and analysis of the fired cartridge cases used in this study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research project is supported by an Australian Government Research Training Program Scholarship. This project is also funded by the NSW Police Force with additional assistance from the UTS Centre for Forensic Science.