CODIS Database

The FBI maintains a national database of offender, arrestee, missing persons, and unknown forensic DNA profiles from unsolved crimes in the National DNA Index System (NDIS).  NDIS contains DNA profiles which have been uploaded by federal, state, and local forensic laboratories. The Combined DNA Index System (CODIS) is the software that is used for matching a DNA profile from a suspect to a profile in NDIS.  CODIS is widely used to solve “cold cases” where DNA testing was not conducted at the time of the original investigation.

Using NDIS Database/CODIS to Prove Innocence

If requested by innocence projects, law enforcement laboratories can use CODIS to electronically compare DNA profiles generated from biological evidence left a crime scene to individuals whose profiles are in NDIS, with the hopes of finding the actual perpetrator of the crime and proving clients’ innocence. As was the case of California Innocence Project client Uriah Courtney, use of CODIS has often revealed that the real perpetrator had committed other crimes while a wrongfully convicted person was incarcerated.

The Issues with Access to CODIS

Permission to use CODIS software is strictly limited, by federal statute, to law enforcement agencies.  Innocence projects do not have the ability or authority to obtain a CODIS upload and their efforts are frequently thwarted by law enforcement and/or prosecutors who refuse to give consent for such an upload.  Without law enforcement’s cooperation, innocent prisoners are deprived access to this valuable investigative tool.

In addition, there are times when a new arrestee’s or convict’s profile is entered into the database and matches a forensic unknown from a crime scene.  If someone else has already been convicted of that crime, there is no requirement that law enforcement disclose this information to the defense.

Familial Searches in CODIS

Family members share DNA.  If a full match cannot be made to a suspect using the CODIS program, police may look at partial matches to determine whether a potential perpetrator’s relative’s profile is in NDIS.  For example, if DNA a perpetrator’s DNA from a rape kit does not match a profile already contained in NDIS, but the perpetrator’s son’s profile is in the system, then a familial search in CODIS could lead police to the son, and ultimately to the perpetrator.

The use of familial DNA searching has been criticized by some civil rights groups.  They claim that such searches constitute an invasion of privacy of the relatives of those whose DNA is already in the system.

Forensic Genealogy

The use of forensic genealogy has gained increased traction in the forensic science community, especially after the use of this tool nabbed the notorious Golden State Killer in California.  When people provide their DNA to companies such as 23andMe or, a DNA profile is generated and users can download their DNA profile. Users can then upload their profile to GEDmatch, a free online DNA database which contains over a million profiles, to search for relatives who have had their DNA tested, but may have used a different company.  In other words, if Person A used and Person B used 23andMe, they would not discover their familial relation. By uploading their DNA profiles to the GEDmatch database, they would discover their relation. In the law enforcement context, law enforcement can develop a DNA profile from a crime scene, upload it to GEDmatch, and develop leads on who the perpetrator may be or who the perpetrator’s relatives may be.