Since current methods used in operational forensic laboratories to identify body fluids lack sensitivity and specificity, this report presents the methodology and findings of a research project that produced markers and methods that can be applied to establishing the source identity of single and mixed biofluids at crime scenes.
Dr. Bruce McCord at Florida International University and colleagues at the University of Southern Mississippi are investigating the role of epigenetic modification in the characterization of various body fluids. Epigenetic modification refers to changes in gene expression not attributed to changes in genetic material. Dr. McCord has identified DNA methylation patterns and subsequently developed epigenetic methylation markers for the detection of various tissue types present in body fluids and dried stains recovered from crime scenes. A method that uses these markers was developed to provide clear quantitative results and has effectively distinguished between tissue types, with the added benefit of sample stability over time. The markers and methods from this research can be applied in establishing the source identity of single and mixed biofluids at crime scenes. This method provides for more specificity than currently used protein-based techniques, because cross-reactivity between body fluids is not an issue. Further, it fits with current DNA analysis methodology, enabling quick, easy interpretation.