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Tools for Improving the Quality of Aged, Degraded, Damaged, or Otherwise Compromised DNA Evidence

NCJ Number
Date Published
August 2014
65 pages
This report presents the methodology and findings of a project whose goal was to develop a new method for repairing double strand breaks in forensic DNA samples as a pre-treatment for the standard STR analysis protocols.
The project developed a protocol that led to increasing/restoring missing or substandard signals at two STR loci. The protocol uses the bacterial RecA protein, single-stranded DNA binding protein (SSB) and bacterial DNA polymerase I, in concert with a targeting oligonuc leotide. The reactions resulting from these reagents restored damaged DNA flanking a particular STR locus. The most developed protocol restored signal approximately 20 percent of the time. With a few exceptions, the restored signals were accurate. The artifacts that arose in the exceptions have been traced to the targeting oligonuc leotides. As part of the work, researchers also developed reproducible procedures for the artificial degradation of human DNA samples, using ionizing radiation to inflict a DNA damage profile that resembles that of a typical degraded forensic sample. 13 figures and 88 references

Date Published: August 1, 2014