Defense Date
2024
Document Type
Directed Research Project
First Advisor
Eric Hazelrigg
Second Advisor
Libby Stern
Third Advisor
Christopher Ehrhardt
Abstract
Using fluorescent polyethylene beads as an analog for trace particulates, five evidence collection techniques were compared to determine their efficacy by the percentages collected and recovered from the initial deposition. The efficacy of each method based on the particle’s size was also assessed. Finally, each method underwent a cost-benefit analysis to evaluate the financial toll that each technique would take on the performing agency.
Trace particulate evidence such as glass fragments, soil, or pollen can establish contextual links between scenes, victims, and suspects. To improve the collection of this evidence, swabbing, tape lifts, dry vacuuming, and pulse lavaging were assessed regarding their efficacy in recovering particulates from fabric.
Three fluorescent bead sizes were used to emulate trace evidence, each with a corresponding color: 10-20 µm (green), 53-63 µm (violet), and 125-150 µm (blue). After depositing the beads on a piece of black cotton fabric, NIS-Elements BR was used to generate photomosaic images under fluorescent microscopy. These were used to count the initial and post-collection numbers of beads to assess each method’s removal and recovery efficacies.
The pulse lavage proved to be a viable instrument for collecting particulate evidence with the greatest removal percentage at an average of 98.6±2.4% across particle sizes. It also demonstrated the greatest percentages of particles recovered from the collection medium and initial deposition (50.0±18.4% and 49.4±18.4%, respectively). Medium-sized particles showed the greatest collection and recovery percentages overall, but there was variation in what sizes were best collected or recovered on a method-by-method basis.
Rights
© The Author(s)
Is Part Of
VCU Master of Science in Forensic Science Directed Research Projects
Date of Submission
12-13-2024