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Toward Locard's Exchange Principle: Recent Developments in Forensic Trace Evidence Analysis

NCJ Number
Analytical Chemistry Volume: 91 Issue: 1 Dated: 2019 Pages: 637-664
Date Published
November 2018
18 pages

This article identifies and profiles developments in forensic trace evidence analysis between 2016 and 2018, including improvements to existing techniques and the introduction of novel methods for the analysis of fibers, hair, paint, glass, gunshot residue (GSR), and explosives.


Such forensic analysis is based on Locard's exchange principle, which states that whenever two objects come into contact with one another, an exchange of materials occurs between them. This may lead to a connection between a suspect and a crime scene or a suspect and a victim, based on transferred fragments of materials. Overall, the article concludes that during the years examined, a variety of scientific tools alone or in combination have demonstrated potential for improving the field of trace evidence examination. Analytical chemistry has made advances in developing and implementing new forensic methods. Recent work on physical evidence analysis has focused on improving the existing technologies and developing novel approaches for examination. There has been movement toward non-destructive, in-field analysis of trace evidence materials; however, in cases where extraction is required, chromatography is still used. Chemometric approaches were found to be useful in recent research, mostly in combination with spectroscopic methods. Many emerging technologies for the forensic examination of trace evidence materials are noted in this article. Spectroscopy has multiple advantages due to its potential for non-destructive analyses. Infrared (IR) spectroscopy and spectroscopic imaging have played an important role in forensic science. Non-invasive hair examination has used ATR FT-IR spectroscopy. Regarding GSR evidence, the authors of this article are involved in applying hyperspectral imaging for the detection of GSR particles. One of the most advantageous techniques for the analysis of explosives is being developed by the Asher group. Micro-SORS technology has been used to examine paint evidence. 10 figures and 233 references

Date Published: November 1, 2018