Defense Date
2026
Document Type
Directed Research Project
Department
Forensic Science
First Advisor
Susan A. Greenspoon, Ph.D.
Second Advisor
Catherine Connon, Ph.D.
Third Advisor
Christopher Ehrhardt, Ph.D.
Fourth Advisor
Stephanie Barnhouse Walcott, M.S.
Abstract
The recovery of touch DNA from handled cartridge casings remains a significant challenge in forensic biology due to low DNA quantification, degradation, and substrate-related inhibition. This study evaluated five DNA extraction methods to improve DNA recovery and STR profiling success from fired and unfired cartridge casings composed of brass and nickel: Virginia Department of Forensic Science (VDFS), Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), a combined ATF/VDFS approach, the ATF method modified with Casework Extraction Buffer (ATF/CEB) and the Broward County method. A total of 238 casings were processed and 81% of those casings had quantifiable DNA on them.
Results showed that the ATF method produced the most successful DNA recovery and STR profile recovery achieving an average STR profile completeness by about 93% for unfired samples and 66% in the fired samples. The enhanced performance is attributed to the inclusion of bovine serum albumin (BSA) and Gly-Gly-His (GGH) together which likely reduced metal ion inhibition. Unfortunately, this method is very labor intensive and less compatible with high throughput laboratory workflows. The VDFS method did have a lower DNA yield comparatively, but it maintained consistency, reproducibility, and compatibility with automation. The combined ATF/VDFS method showed poor reproducibility due to reagent incompatibility that caused precipitate formation, and lastly the ATF/CEB method also lacked consistency with both DNA quantification and STR profile recovery. Across all methods the fired casings generally produced lower DNA recovery than unfired, but the differences were not always statistically significant.
Rights
© The Author(s)
Is Part Of
VCU Master of Science in Forensic Science Directed Research Projects
Date of Submission
7-9-2026