Microfiber Alignment in Stamp Edges for Physical Fit Comparisons

Colton Diges*, Zachary Andrews, Meghan Prusinowski, and Tatiana Trejos
Department of Forensic and Investigative Sciences, West Virginia University, Morgantown, WV, 26505

Presentation No.: 101

Assigned Category (Presentation Format): Physical Sciences (Poster Presentations)

Student’s Major: Forensic Chemistry

Postage stamps are important evidence for investigations of mail-related crimes as they may provide an association between a letter and a suspect. Stamps have reproducible edges, so edge appearance cannot be used to identify a single source. Instead, current practice is to examine both stamp edges for potential aligning microscopic fibers. Stamps that fit together are assumed to have microfibers that continue across the edge, while non-fitting stamps would not. However, this assumption has yet to be demonstrated in literature. This study developed a systematic method to determine the location and number of aligning microfibers between stamps. 100 pairs of stamps were blindly evaluated by two independent examiners, and the performance was assessed along with the distribution of observed microfibers. Overall, the average number of fibers in a fitting pair was 53 (± 39), much higher than non-fitting pairs with an average of 2 (±2). The accuracy of the two examiners was 94-96%, with a misidentification rate between 2-8%. These findings indicate that microfiber orientation alignment with appropriate thresholds can support the examiner’s opinion.

Funding:

Program/mechanism supporting research/creative efforts: WVU's SURE program (Rita Rio & Michelle Richards-Babb)