About the seminar:
Accurate evaluation of gunshot residue (GSR) evidence in criminal investigations requires a deep understanding of its deposition, transfer, and persistence. This seminar presents research from West Virginia University on modernizing GSR examinations. The studies demonstrate how traditional SEM-EDS analysis is complemented by modern analytical techniques—including laser-induced breakdown spectroscopy (LIBS), electrochemical sensors, and LC-MS/MS—to deliver faster, more accurate screening in both field and laboratory settings.
Using laser scattering, high-speed imaging, particle counters, and natural and synthetic skin models alongside shooting trials, this research evaluates over 3,000 samples to track the physical behavior of inorganic (IGSR) and organic (OGSR) residues across various substrates and post-shooting scenarios. The findings offer essential empirical baselines to help forensic scientists improve evidence recovery, protect sample integrity, and evaluate evidence under competing investigative hypotheses.
Finally, the presentation discusses how the performance metrics of these analytical workflows provide a scientific foundation for courtroom defensibility and how these modern tools can improve efficiency in the criminal justice system.
Speaker Bio:
Dr. Trejos is a Professor in the Department of Forensic and Investigative Sciences at West Virginia University. Dr. Trejos’ research develops methods that enhance the reliability and efficiency of trace evidence, providing valuable data to the criminal justice system and streamlining processes. Dr. Trejos’s main research includes applying statistics to evidence interpretation and discovering chemical signatures of forensic materials using spectrochemical methods, such as SEM-EDS, ICP-MS, Laser Ablation ICP-MS, µXRF, LIBS, and Mass Spectrometry (GC-MS and LC-MS). Glass, paints, polymers, inks, and gunshot residues are among the trace materials investigated in Dr. Trejos’ laboratory. Dr. Trejos has received funding from the U.S. Department of Justice, the National Institute of Justice, the US Department of State, and the Department of Commerce. Tatiana Trejos has authored 101 peer-reviewed scientific publications and book chapters in forensic and analytical chemistry. Dr. Trejos has served as a program chair for scientific meetings and as a guest speaker at several venues worldwide. Dr. Trejos serves as an expert to numerous national and international organizations, developing consensus-based guidelines, testing methods, and best practices; identifying research and development needs; and implementing advanced technology and quality management in forensic laboratories. Dr. Trejos is the Chair of the TRACE Dr. Trejos has received prestigious awards such as the “Clodomiro Picado Twight” from the Costa Rican National Academy of Sciences (2015), the WVU Eberly College Outstanding Researcher Award (2020), the Sharon B. Nakich Award from NIST-OSAC (2024), the Travis Stimeling Award for Mentoring Undergraduates in Research in the category of Physical Sciences & Technology (2025), and the Edmond Locard Award for Excellence in Trace Evidence from the American Society of Trace Evidence Examiners, ASTEE (2025). Tatiana was elected as ASTEE President (2027) and was appointed Chair of the Trace Evidence Scientific Area Committee (SAC), overseeing the ILEGSR(ignitable liquids, explosives, and gunshot residue) and Trace Materials (geology, interpretation, glass, paint, fibers, physical fits, paint, and polymers) subcommittees.
