Further Development of Raman Spectroscopy for Body Fluid Investigation: Method Advancement and Validation

As submitted by the proposer: Currently, the methods used to identify body fluids in forensic investigations are either presumptive or destructive to the evidence. A universal test that could identify any body fluid at a crime scene without destroying it would be an extraordinary breakthrough in forensics. Our research group has demonstrated the tremendous potential of combining Raman spectroscopy and chemometrics for body fluid analysis. The proposed research has two overall goals; to advance and validate this work. Method advancement will be accomplished by establishing a standard preprocessing procedure and creating a classification model to identify body fluids, and by developing new capabilities for body fluid characterization. First, Raman spectra will be collected from the five main body fluids; peripheral blood, saliva, semen, sweat, and vaginal fluid. These spectra will be used to calibrate and externally validate statistical models. Next, Raman spectra will be collected from semen, sweat, and saliva donors, and used to build chemometric models to differentiate donors according to race and gender. All models will be externally validated with test datasets. Method validation will be performed by testing the current protocols with a handheld Raman instrument, and by establishing the limit of detection. Sample preparation will be carried out by serially diluting body fluids to create a set of standard solutions. The spectra will then be tested with the developed model in order to determine if the body fluids can be detected. After our experimentation, the samples will then be submitted to our collaborators at the New York State Police Crime Lab System for DNA analysis to confirm whether or not laser irradiation damages the DNA contained within body fluid traces. Finally, body fluids will be analyzed using a handheld Raman spectrometer and the spectra will be used to test the new model. The handheld spectrometer will be provided by our collaborators at the Defense Forensic Science Center at the Department of the Army. This investigation will inform us whether or not the current method is applicable to data collected by on-field instrumentation. Any necessary adjustments will be made so that the method is not dependent on the instrumentation used. Achieving these two goals will help to improve the current work and move it one step closer to practical implementation. All results from the proposed research will be submitted to peer-reviewed publications and included in semi-annual reports to the NIJ. The data that is collected will be archived according to NIJ requirements. This project contains a research and/or development component, as defined in applicable law. nca/ncf.