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Forensic DNA Education for Law Enforcement Decisionmakers

Familial Searching

What is Familial Searching?

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Familial searching is a process by which a DNA profile of interest in a criminal case is searched against the database. If there are no direct matches, it is then searched again in an attempt to find DNA profiles that are similar to the profile of interest and could belong to a close relative of the person who left the DNA at the crime scene. There are two parts to the process. First, the software ranks candidate relatives in order of likelihood that they are closely related to the person who left the DNA. There will always be an appreciable number of candidates on this list. Next, all of the candidates' samples are subjected to additional DNA typing, using existing Y-chromosome testing. This testing can strongly establish the existence of a close familial relationship (typically father-son or brother-brother) between the person who left the evidence and the individual in the database of person convicted of or arrested for a crime.

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