Combined DNA Index System - Indices and Database Structure

Indices and Database Structure

CODIS is an index of pointers to assist US public crime laboratories to compare and exchange DNA profiles. A record in the CODIS database, known as a CODIS DNA profile, consists of an individual's DNA profile, together with the sample's identifier and an identifier of the laboratory responsible for the profile. CODIS is not a criminal history database, like the National Crime Information Center (NCIC), and does not contain any personal identity information, such as names, dates of birth, and social security numbers.

Originally, CODIS consisted of the Convicted Offender Index and the Forensic Index, but in recent years, the Arrestee Index, the Missing or Unidentified Persons Index, and the Missing Persons Reference Index have been added. The Convicted Offender Index contains profiles of individuals convicted of crimes. State law governs which specific crimes are eligible for CODIS. (All 50 states have passed DNA legislation authorizing the collection of DNA profiles from convicted offenders for submission to CODIS.) The Forensic Index contains profiles developed from biological material found at crime-scenes.

CODIS has a matching algorithm that searches the various indexes against one another according to strict rules that protect personal privacy. For solving rapes and homicides, for example, CODIS searches the Forensic Index against itself and against the Offender Index. A Forensic to Forensic match provides an investigative lead that connects two or more previously unlinked cases. A Forensic to Offender match actually provides a suspect for an otherwise unsolved case. It is important to note that the CODIS matching algorithm only produces a list of candidate matches. Each candidate match is confirmed or refuted by a Qualified DNA Analyst. (To become Qualified, a DNA Analyst must meet specific education and experience requirements and undergo semi-annual proficiency tests administered by a third party.)

CODIS databases exist at the local, state, and national levels. This tiered architecture allows crime laboratories to control their own data—each laboratory decides which profiles it will share with the rest of the country. As of 2006, approximately 180 laboratories in all 50 states participate in CODIS. At the national level, the National DNA Index System, or NDIS, is operated by the FBI at an undisclosed location.