Research: Evaluation of Familial Search Software for Forensic Investigation using Mutation Rate Adjusted Synthetic Data Sets

The use of a national DNA database, such as CODIS (Combined DNA Index System), to provide leads in unidentified missing persons and violent crime cases can be an advantageous tool for investigators nationwide.  When a search of such a database yields no “hit,” investigators are not necessarily left with a dead end.  Familial searching of DNA databases uses specialized software to examine the database for possible relatives of the individual who contributed to a questioned DNA profile obtained at a crime scene by searching the genetic information of the convicted offenders already in the database.  A list of likelihood ratios are ranked and compiled in order to predict the possible biological relationship of the questioned profile and the resulting partial matches from the database.  The focus of this research will be concentrated on how known microsatellite mutation rates at the CODIS core loci affect the familial search software’s ability to return the correct familial relationships.  The researchers will evaluate variables associated with mutation rates in STR, Y-STR (Y-chromosome DNA) and/or mtDNA (mitochondrial DNA) markers in software.  To do this, the researchers will be generating synthetic families to test kinship and sibship analysis while manipulating the mutation rates within the software to reflect those, which are now published.  Practical considerations such as success rate, false positives rates, false negatives rates, cost of analysis and time will be thoroughly evaluated.  Socio-ethical issues will also be explored involving the legality issues of states permitting familial searching with the current software validation capabilities.