Defense Date
2026
Document Type
Directed Research Project
First Advisor
Stephanie Walcott
Second Advisor
Curtis Marshall
Third Advisor
James Bogenpohl
Abstract
Shotguns discharge either multiple projectiles (pellets or “shot”) or a single slug. When fired, pellets disperse from the muzzle, producing a characteristic spread pattern on the target. The configuration of this pattern is influenced by variables such as barrel length, choke, ammunition type, and muzzle-to-target distance. When a complete pellet pattern is available, forensic firearm examiners typically compare the questioned pattern to test-fired patterns to estimate shooting distance, most often relying on overall pattern diameter. However, partial patterns present a significant challenge, as traditional diameter-based methods are not applicable. Only one manual method based on pellet-to-pellet distance measurements has been described in the literature, with limited subsequent research.
This study addresses two primary objectives. First, it validates and expands a previously developed quantitative method using ImageJ, an open-source image analysis software, to measure pellet-to-pellet distances in both full and partial patterns. This approach enables pixel-level precision, promoting greater objectivity and reproducibility in distance estimation. Second, the study introduces a novel method for partial patterns based on the pellet-to-surface area ratio, allowing analysis even on irregular substrates.
Findings demonstrate that these quantitative techniques reduce examiner subjectivity and expand the applicability of distance determination methods, particularly when complete patterns are unavailable. This research supports the advancement of standardized, evidence-based practices in forensic shotgun pattern analysis.
Rights
© The Author(s)
Is Part Of
VCU Master of Science in Forensic Science Directed Research Projects
Date of Submission
5-7-2026