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Principles of Forensic DNA for Officers of the Court

"Cold Hits" and Probable Cause

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illustration of horizontal DNA double helix with the text "COLD HIT" in the foreground
National Institute of Justice (NIJ) (see reuse policy).

When DNA evidence is recovered from a crime scene, time may pass, even years, before comparison with a known DNA sample identifies the source of the DNA evidence. This is known as a cold hit. Cold hits are database matches that identify someone who was not previously suspected.

The DNA match establishes probable cause for an arrest and may permit an arrest even if the statute of limitations has expired.

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