Defense Date
2025
Document Type
Directed Research Project
First Advisor
Dr. Christopher Ehrhardt
Second Advisor
Kate Philpott, J.D.
Third Advisor
Dr. Julie Burrill
Abstract
Dogfighting is a felony in all 50 states and is often tied to other organized crime activities including gambling, narcotics, and weapons trafficking. Because of the clandestine nature of dogfighting crimes, it may be necessary to determine the age of blood samples from suspected events, not just the source. In this study, flow cytometry was used to identify cellular autofluorescence signatures for estimating TSD (time-since-deposition) in canine blood deposits up to 6 months old. To accomplish this, blood was taken from canines of various chronological ages and breeds, then deposited to create TSD samples ranging between 1 day and 180 days. Autofluorescence profiles of individual cells were characterized using a 488nm excitation laser and detector wavelengths between 535nm-700nm. Fluorescence histograms showing the number of cells at varying intensities were used to compare cell populations at different TSDs. Results showed that canine blood samples exhibited high fluorescence at 523nm, 583nm, and 695nm within a week of deposition (e.g. 104 RFU at 3 days, 103 RFU at 7 days) compared to freshly deposited samples. After one week, fluorescence intensity continued to increase up to 30 days. After 90 days, all contributor cell populations showed a two-fold decrease in autofluorescence intensity. These results suggest that autofluorescence signatures can potentially be used to estimate TSD of canine blood samples, which may be probative for many types of animal fighting investigations.
Rights
© The Author(s)
Is Part Of
VCU Master of Science in Forensic Science Directed Research Projects
Date of Submission
5-10-2025