Today's Messages

The Chemistry Department will host a graduate student Master's Project seminar on Thursday, May 7, during Bengal Pause (12:15 to 1:30 p.m.) in SAMC 151. Our speaker will be Anna Killingbeck, a graduate student in the forensic science master's program. 

Title: Forensic Characterization of Trace Polymer Transfer from 3D-Printed Firearm Components to Cartridge Casings

As the prevalence of privately made firearms (PMFs) increases, the forensic analysis of 3D-printed components becomes vital for ballistic identification and trace evidence recovery. This study investigates the mechanisms of polymer transfer from various 3D-printed materials to shell casings during the firing and ejection process. Nine polymer types—including TPU, PET-G, Nylon, ABS, ASA, PLA, PLA+, PLA-Carbon Fiber, and PLA-Wood Fiber—were examined to evaluate their potential as trace evidence sources.

Two primary transfer pathways were simulated: internal magazine transfer via plastic shims to unfired cartridges, and external transfer occurring when hot, ejected casings struck polymer surfaces. Preliminary screening was conducted using comparison microscopy to locate potential polymer deposits. Subsequent analysis utilized Scanning Electron Microscopy (SEM) and Reflectance Spectroscopy to characterize the chemical and structural morphology of the transferred material.

This presentation details the analytical methodology, the performance of the various polymers under thermal and mechanical stress, and the efficacy of the instrumentation in identifying polymer traces on metallic surfaces. The findings highlight pitfalls in analysis methods and suggest future avenues for research, including the integration of additional spectroscopic techniques to enhance the discriminatory power of polymer trace evidence in forensic ballistic investigations.