Defense Date
2026
Document Type
Directed Research Project
First Advisor
Stephanie Walcott
Second Advisor
Bob Zinn
Third Advisor
Rosemary Harton
Abstract
Visualization of lead gunshot residue (GSR) patterns on dark or patterned fabrics remains a persistent challenge in firearm muzzle-to-target distance determinations. Although the Sodium Rhodizonate test is widely used for lead detection, the Bashinski transfer method of this technique can result in loss of visible residue compared to the direct application technique. This study evaluated non-destructive photographic enhancement techniques, including infrared (IR) imaging and alternate light source (ALS) illumination, for application in muzzle-to-target distance determination. In addition, the Trace Metal Detection Technique (TMDT), a historically used forensic method for detecting metal residues on skin or clothing through chemical treatment and ultraviolet visualization, was also assessed.
Controlled test fires were conducted using caliber 22 Long Rifle lead round nose (LRN), caliber 9mm Luger full metal jacket (FMJ), and caliber 40 S&W total metal jacket (TMJ) ammunition fired from semiautomatic pistols at muzzle-to-target distances of three (3), six (6), twelve (12), eighteen (18), and twenty-four (24) inches. Target materials included white cotton twill, black cotton twill, and black rayon/spandex fabrics. IR and ALS photography were performed prior to chemical processing. Sodium Rhodizonate direct application served as the primary chemical detection method, with the Bashinski transfer technique applied to dark fabrics; TMDT was evaluated under ultraviolet illumination.
Photographic methods improved visualization on dark or patterned fabrics, particularly ALS at approximately 455 nm. TMDT demonstrated potential as a direct-application alternative to the Bashinski transfer, though limitations and chemical safety concerns were identified. Further research is needed to assess false positives and potential interference from bodily fluids.
Rights
© The Author(s)
Is Part Of
VCU Master of Science in Forensic Science Directed Research Projects
Date of Submission
5-6-2026