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Automation of the Differential Digestion Process of Sexual Assault Evidence

NCJ Number
Journal of Forensic Sciences Volume: 64 Issue: 2 Dated: 2019 Pages: 539-550
Date Published
12 pages
Since sexual assault evidence samples require the use of a specific process known as a differential digestion to separate sperm from non-sperm cells prior to DNA extraction, this project developed an automated differential digestion process, using a selective degradation technique, which uses DNase I to digest the remaining non-sperm DNA in the sperm fraction.

The use of DNase on pristine samples, as well as aged and degraded samples, was assessed to ensure that the quantity and quality of the sperm DNA were not compromised or adversely affected. Samples processed using the selective degradation technique yielded comparable DNA yield and DNA typing data to the conventional differential digestion process. The automated process utilized 96 well plates for high throughput and incorporated microscope slide preparations for confirmation of sperm. It reduced processing time by about sixfold and was paramount in the elimination of the Oakland Police Department Criminalistics Laboratory's sexual assault kit backlog. (publisher abstract modified)

Date Published: January 1, 2019