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Familial DNA Database Search System-Hardware/Software Integration Project

NCJ Number
Date Published
July 2017
29 pages
This report presents the findings and methodology of a study that attempted to improve current familial DNA search approaches, which has the potential to leverage forensic DNA databases to detect siblings and parent-child relatives with existing short tandem repeat (STR) based data.

The project had two main goals. The first was to develop a web-based familial DNA search system that enables secure data transmission through a graphical interface for determination of family relatedness that can be used by law enforcement crime laboratories nationally. A second goal was to conduct statistical evaluations of familial searching to produce additional recommendations for interpretation of results and potential improvement in likelihood ratio calculations. Project results show that evaluation of all genetic information increases the identification of true familial pairs when conducting familial searches. The study's data also indicate that adjustment of likelihood ratios to account for database size can be counterproductive. Selecting a statistically relevant threshold is also critical in the determination of familial matches, and selecting one based on a specific false positive rate should be pursued more formally. This study also recommends that the current implementation of familial searching ranking statistics used by the Denver Police Crime Laboratory be used for maximizing useful results. It was collaboratively developed by the Denver Police Department and the Denver District Attorney's Office to compile, search, and report potential familial relationships from existing forensic DNA data stored in the CODIS databank. 15 tables, 12 figures, and 34 references

Date Published: July 1, 2017