Race Differentiation by Raman Spectroscopy of a Bloodstain for Forensic Purposes

• NCJ Number: 251231
• Author(s): E. Mistek, L. Halamkova, K. C. Doty
• Date Published: August 2016
• Length: 4 pages
• Agencies: NIJ-Sponsored
• Award: Raman spectroscopy for analyzing body fluid traces, stain aging, differentiation between races, genders and species; Raman spectroscopy for analyzing body fluid traces: Moving towards a practical forensic application

Annotation

Bearing in mind forensic purposes, this article describes the development of a nondestructive and rapid method for race differentiation of peripheral blood donors.

Abstract

Blood is an extremely valuable form of evidence in forensic investigations, so proper analysis is critical. Because potentially miniscule amounts of blood traces can be found at a crime scene, having a method that is nondestructive and provides a substantial amount of information about the sample is ideal. In this study, Raman spectroscopy was applied with advanced statistical analysis to discriminate between Caucasian (CA) and African-American (AA) donors based on dried peripheral blood traces. Spectra were collected from 20 donors varying in gender and age. Support vector machines-discriminant analysis (SVM-DA) was used for differentiation of the two races. An outer loop subject-wise cross-validation (CV) method evaluated the performance of the SVM classifier for each individual donor from the training data set. The performance of SVM-DA, evaluated by the area under the curve (AUC) metric, showed 83 percent probability of correct classification for both races, and a specificity and sensitivity of 80 percent. This preliminary study shows promise for distinguishing between different races as contributors of human blood. The method has potential for real crime-scene investigation, providing rapid and reliable results, with no sample preparation, destruction, or consumption. (Publisher abstract modified)