In this paper, the authors investigate the use of Raman spectroscopy to examine bloodstains for forensic purposes.
After reviewing recent developments in forensic trace evidence analysis, this thesis discusses the results of experimental work on race differentiation using Raman spectroscopy of a bloodstain for forensic purposes. This preliminary study shows promise for distinguishing between different races of human blood. This method has great potential for real crime scene investigation, providing rapid and reliable results, with no sample preparation, destruction, or consumption. Bearing in mind forensic purposes, a nondestructive and rapid method was developed for race differentiation of peripheral blood donors. 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. 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 (SVMDA) 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 SVMDA, evaluated by the area under the curve (AUC) metric, showed 83% probability of correct classification for both races, as well as a specificity and sensitivity of 80%.
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