Combining Morphological and Chemical Identification for the Interrogation of Forensic Traces

The detection and analysis of traces for the purpose of providing clues in criminal investigations has a rich history that dates back to the mid-18th Century.  Traces are remnants of past events that provide both associative and investigative information, however the quality and quantity of information that can be obtained from their interrogation depends on both the tools (or instruments) being used and the expertise of the examiner.  The traditional tool of light microscopy provides valuable physical and optical properties of a material that can aid in its identification and comparison.  When paired with instrumental methods for chemical analysis, most notably in the forms of infrared and Raman microspectroscopy, a plethora of valuable information can be obtained from a range of traces. Further, new developments in instrumentation, such as morphologically-directed Raman spectroscopy (MDRS), particle-correlated Raman spectroscopy (PCRS) and simultaneous Optical Photothermal Infrared & Raman (O-PTIR+R) microspectroscopy, have enabled more information to be obtained from the analysis of complex samples than could be previously obtained.  This presentation will demonstrate the interrogating power of these new tools for the analysis of a range of samples of forensic interest, including illicit and counterfeit drugs, soils, gunshot residue (GSR), hoax white powders, and automotive paint.

Learning Objectives:

1. Describe the variety of traces that deliver valuable associative and investigative information for forensic inquiries

2. Discuss new developments in instrumentation, including MDRS, PCRS and O-PTIR+R.

3. Understand the added value provided when traces are analyzed with MDRS, PCRS and O-PTIR+R