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Molecular Characterization of Trace Biological Evidence for the Optimized Recovery and Analysis of 'Touch DNA'

NCJ Number
Date Published
September 2014
94 pages
In order to better characterize the biological material present in touch DNA evidence, the project presented in this report developed a "micro-particle atlas" that contains thousands of images of bio-particles recovered from various clothing items, household items, and touched objects.
Uncertainty regarding the source of trace biological material is being used by defense attorneys in some criminal proceedings in an attempt to diminish the significance of trace biological evidence. Thus far, research has failed to provide crime laboratories with feasible methods for identifying the tissue source of origin of touch DNA samples. The micro-particle atlas developed by the current project provides images of bio-particles that permit an assessment of the morphological features of bio-particles in touch DNA evidence, enabling researchers to assess the type and quantity of cellular material present. The project is currently attempting to make this atlas available online, since it could be useful reference material for operational crime laboratories in support of their analysis of touch DNA evidence. This project improved collection and profiling strategies for the recovery and analysis of bio-particles in touch DNA evidence. Collection strategies included the transfer of the biological material from touched objects and surfaces to a low-retention adhesive material and isolation of single or few bio-particles or cells using a water soluble adhesive. The use of the water-soluble adhesive permits the transfer of the recovered particles to a lysis buffer or directly into a PCR amplification reaction. An improved one-step micro-volume (5 ml) lysis/STR amplification reaction enables the recovery of full or probative STR profiles of the donor of single or few bio-particles. The project also demonstrated the ability to apply the developed collection and micro-volume profiling strategies to detect the male donor in simulated physical assault mixture samples. 46 figures, 39 references, and a listing of presentations derived from the project

Date Published: September 1, 2014