Touch DNA in Activity-Level Propositions: A Bullpen of Events to Inform Alternate Prosecution and Defense Scenarios

Providing alternate scenarios to explain why a suspect’s DNA is found at a crime scene is a common form of defense, and evaluating each scenario provides tremendous value when it can be backed by empirical data.  The goal of the proposed research is to eliminate the variation of DNA quantity in the original touch sample deposition by creating a ground truth sample, the domesticated fingerprint, containing a known quantity of DNA in sebaceous fingerprint chemistry.  Knowing the starting DNA quantity in a touch sample, we will define specific transfer events, as well as chains of events, by DNA transfer and recovery.

In Aim 1, the ground truth sample will be expanded to include a domesticated hand, a mock epidermis molded on a nitrile glove.  We will establish a workflow for the use of the domesticated hand and fingerprints and demonstrate its application with a 2-event transfer pathway.  A fingerprint will be deposited, collected by swabbing, the DNA extracted, quantified and amplified as a STR multiplex.  Fingerprints in the wild, i.e. natural fingerprints, will be analyzed to compare and contrast.  In Aim 2, we will complete a more complex transfer pathway with both domesticated and wild fingerprints.

The data will be used to establish a “bullpen of transfer events,” each supported by empirical transfer and recovery data, which would be informative in a variety of crime scenarios and, therefore, be of great use to the forensic scientist.  The options bullpen will support a flexible predictive model that will enable a forensic scientist to objectively evaluate the potential for DNA profiles to be generated by a variety of potential scenarios.  The result will be of tremendous value to the forensic and justice system communities, as currently this type of transfer is only postulated, with no objective means of quantitation.  Therefore, it is a major step forward in supporting justice through objective data to evaluate competing crime reconstruction scenarios.

This work has grown from a long-term collaboration between an academic lab (UC Davis) and an operational forensic lab (NYC State Crime Laboratory).  Products and deliverables will include quarterly financial reports, semi-annual and final progress reports.  A bullpen of events and predictive model supported by publicly available empirical data, will be made available to the forensic science community in open-access journals.  The data will be presented at national forensic sciences conferences and in peer-reviewed publications.

Note: This project contains a research and/or development component, as defined in applicable law," and complies with Part 200 Uniform Requirements - 2 CFR  200.210(a)(14). CA/NCF