Date of Submission
5-2026
Document Type
Thesis
Degree Name
Master of Science in Forensic Science
Department
Criminal Justice
Advisor
Peter Valentin, Ph.D.
Committee Member
Virginia Maxwell, Ph.D.
Committee Member
Lisa Ragaza, M.S.
Keywords
Gunshot Residue (GSR) Location, Nitrite Distribution, Barrel LengGunshot Residue (GSR) location, Nitrite Distribution, Barrel length, Firearm orientation, Video spectral comparator (VSC), Particle distribution quantification th, Firearm orientation, Video Spectral Comparator (VSC), Particle Distribution Gunshot Residue (GSR) location, Nitrite Distribution, Barrel length, Firearm orientation, Video spectral comparator (VSC), Particle Distribution Quantification
MeSH
Wounds, Gunshot, Firearms, Nitrites, Image Processing, Computer-Assisted, Spectrometry, Fluorescence
LCSH
Gunshot residues, Forensic sciences, Firearms -- Identification, Image processing -- Digital techniques, Fluorescence spectroscopy
Abstract
When a firearm is discharged, both organic and inorganic gunshot residue (GSR) are expelled through the firearm’s openings and deposited on nearby surfaces. Primer GSR (pGSR), a component of inorganic GSR, consists of lead, barium, and antimony, whereas organic residue is composed of nitrocellulose and/or nitroglycerin. Nitrites, although derived from organic compounds, are inorganic byproducts of propellant combustion and can be detected using the Modified Griess, Walker, and Marshall tests. Given their relative abundance and inherent fluorescence, nitrite residues provide a useful proxy for assessing pGSR distribution (Wallace, 2018). Mapping nitrite distribution may help identify locations with the greatest likelihood of containing pGSR for sampling. This study hypothesizes that barrel length and orientation will affect how GSR is distributed onto the shooter, such that either another location in addition to the dominant arm or a different location entirely should be sampled on a shooter’s body for collecting GSR.
Controlled firings were conducted with the shooter firing wearing long-sleeved black shirts using two firearms of the same caliber and manufacturer but with different barrel lengths, and the firearm held at two different orientations. After discharge, the shirts were removed and photographed under a video spectral comparator (VSC) to capture nitrite fluorescence using a selected wavelength band and barrier filter combination. Images were processed using a Python algorithm to isolate fluorescent particles and quantify distribution across shirt regions, which were visualized through heatmaps. Results indicate distinct variations in GSR distribution for barrel length and, more prominently, orientation. These findings highlight the need to consider certain variables when collecting GSR, thereby improving detection reliability and reducing false negatives.
Recommended Citation
Miller, Emily J., "The Impact of Barrel Length and Firearm Orientation on Gunshot Residue Distribution Patterns on a Shooter" (2026). Master's Theses. 276.
https://digitalcommons.newhaven.edu/masterstheses/276