Date of Submission
Master of Science in Forensic Science
Raman spectroscopy, Gunshot residues
Gunshot residue (GSR) can be an indicator for determining the distance of a firearm discharge and linking potential suspects and witnesses to a shooting event. However, the evidentiary value of inorganic gunshot residue (IGSR), commonly used to detect GSR, has been called into question due to the potential for false negatives and false positives. Organic gunshot residue (OGSR) acts as supporting evidence; this increases the overall confidence of the examiner, as well as the value of gunshot residue evidence as a whole.
Current research has focused on three main areas for OGSR. The first is what compounds we should identify as relevant and in enough quantity to reliably find at the scene. Next, is how to collect OGSR. Standard swabs and different styles of aluminum stubs have been tested and validated. Lastly, is the type of instrumentation to be used. Currently, research is focusing on the use of high-performance liquid chromatography paired with mass spectrometry (HPLCMS), gas chromatography paired with mass spectrometry (GCMS), and multiple spectroscopy techniques.
This study aims to validate the identification of six common OGSR compounds contaminated with blood using gas chromatography paired with mass spectrometry (GCMS), Raman spectroscopy, and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR). For each instrumentation, samples were analyzed separate of blood contamination or substrate. Then, they were analyzed in relation to 100% cotton substrate. Lastly, they were analyzed with blood contamination. GCMS showed masking for 2-4 Dinitrotoluene, Raman interpretation was not possible, and a majority of ATR-FTIR results were masked.
Willits, Tyler, "Investigating the Masking Effects of Blood on Organic Gunshot Residue Using GC/MS, Raman, and ATR-FTIR" (2019). Master's Theses. 104.