Two-year review of firearm-related DNA casework evidence: A triage process to improve quality and efficiency

A two-year casework review of 617 firearm-related submissions representing 119 cases has provided a DNA testing triage template for prioritizing and processing touch evidence associated with firearms and firearm accessories. The evidence consisted of swabbings from various locations of a firearm or a firearm-related item, and each submission was assigned to one of the following descriptive groups: Body, Magazine, Trigger Area, Rifles, Gun Accessories, Barrel, Miscellaneous, or Revolvers. Ultimately, there were 543 submissions analyzed from DNA extraction through electrophoresis, and interpretable profiles evaluated to determine eligibility for entry into The Combined DNA Index System (CODIS). All samples were subjected to the same validated DNA technologies and methodologies used in the laboratory during the study's February 2020 through February 2022 time period, allowing for direct comparison of data. A DNA profile, defined as the detection of at least one allele above the analytical threshold, was detected in 478 samples (88%). Interpretable profiles, defined as a DNA profile that, as a whole or in part, is deemed to be of sufficient quality that it is suitable for comparison to known DNA standards for the purpose of inclusion or exclusion, were observed in 287 samples (53%). In this sample set, there were 12 DNA profiles generated from nine different cases that were uploaded into CODIS, resulting in three CODIS hits. Additionally, there were 163 standards associated with these cases that were entered into CODIS. As a result of this extensive review, the data strongly supported modifications to both the Forensic Biology Unit's firearm-related Case Submission Policy and the laboratory's DNA process for triaging samples from firearms.