LDIS, SDIS, and NDIS

CODIS is implemented as a distributed database with three hierarchical levels (or tiers)—local, State, and national. All three levels contain forensic and convicted offender indexes and a population file (used to generate statistics). The hierarchical design provides State and local laboratories with the flexibility to configure CODIS to meet their specific legislative and technical needs.

A description of the three CODIS tiers follows (see exhibit 2).

• Local. Typically, the Local DNA Index System (LDIS) installed at crime laboratories is operated by police departments or sheriffs’ offices. DNA profiles originated at the local level can be transmitted to the State and national levels.
• State. Each State has a designated laboratory that operates the State DNA Index System (SDIS). SDIS allows local laboratories within that State to compare DNA profiles. SDIS also is the communication path between the local and national tiers. SDIS is typically operated by the agency responsible for implementing and monitoring compliance with the State’s convicted offender statute.
• National. The National DNA Index System (NDIS) is the highest level of the CODIS hierarchy and enables qualified State laboratories that are actively participating in CODIS to compare DNA profiles. NDIS is maintained by the FBI under the authority of the DNA Identification Act of 1994.

Some or all of the content on this page was excerpted from the Special Report Using DNA to Solve Cold Cases, developed under an award from the Office of Justice Program's National Institute of Justice. See award product disclaimer.