CODIS: The National DNA Database
The Combined DNA Index System (CODIS) is a database in which DNA profiles from crime scenes and convicted offenders (and, in some states, arrestees) are stored. CODIS — which includes local (LDIS), state (SDIS) and national (NDIS) databases — can be searched to determine if a DNA profile pulled from biological evidence in a crime matches the DNA of a known offender or DNA from evidence in another crime. These searches can generate leads for investigators when matches, or "hits," occur.
As of 2010, CODIS contained more than 8.7 million offender profiles and approximately 330,000 profiles from crime-scene evidence.
Searching CODIS can potentially have both immediate benefits (offering investigative leads in the current case) and long-term benefits (potentially linking an assailant to other crimes or linking cases together). Many states now collect DNA from all felony arrestees, which is greatly expanding CODIS and increasing the opportunity for hits. (For more information on arrestee DNA collection, see "Collecting DNA from Arrestees: Implementation Lessons".)
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