As submitted by the proposer: Due to increased awareness of DNA identification in sexual assaults, and the accuracy of DNA matching, criminals are using condoms to prevent leaving their DNA on the victim. In the absence of DNA, the condom lubricant can be used to link the suspect and the victim.
This project focuses on characterizing the residual lubricants after a sexual assault and understanding how their chemical composition changes from the unaltered sample. Lubricant components that remain on the victims body or at the crime scene will be identified and can be used to indicate sexual intercourse.
In contrast to other studies, both major and minor lubricant components, which are indicative of lubricants versus personal hygiene products, will be the focus. In addition, components that can classify the type of the recovered lubricant will be identified.
The first phase will characterize lubricant samples and identify components that are specific to individual lubricant classes. Samples will be characterized on the DART-TOFMS and 2d-GC-MS because they provide superior baseline separation of individual components versus the traditional GC-MS. The goal is to identify classes based on unique peaks corresponding to the major and minor components.
The second phase will identify the chemical morphology of the lubricant when exposed to common situations. Lubricants will be placed on a skin alternative and analyzed over a 72 hour period to determine the persistence of major/minor components. Samples will also be exposed to different environmental conditions to determine how the lubricant components persist after 5 days. This will be useful to determine how long lubricants will remain on condoms, fabrics, and skin after intercourse.
The recovered lubricants from the environmental and skin persistence studies will be compared to the unchanged lubricants to determine the significance of the chemical degradation, using PCA. Bayesian networks and likelihood ratios will be used to ensure that the classification schematic developed will accurately place the recovered lubricants in the same class as the unchanged lubricant.
The graduate student will lead the characterization, classification and degradation of the lubricants as well as produce publications, presentations, and a dissertation presenting the findings of each milestone. Generated data sets will be archived as .csv files at NACJD and on NCFS website for interested researchers. This classification scheme will lay the foundation for a protocol that forensic analysts can use in the evaluation of trace evidence in sexual assault crimes.
This project contains a research and/or development component, as defined in the applicable law. nca/ncf
