CODIS is the COmbined DNA Index System. Authority for the Commonwealth to participate in CODIS is governed by Massachusetts General Law, Chapter 22E. As of February 10, 2004, this legislation requires all individuals convicted of a felony offense to submit a blood sample to the Massachusetts State Police Crime Laboratory. Following administrative verification of the offender's identity and predicate offense(s) in the criminal history, the sample is tested and the profile is then entered into a State and National CODIS databank.
This system is similar to the existing index of traditional fingerprint files maintained and compared across the nation (i.e. AFIS). Both the Massachusetts State Police and Boston Police Department Crime Labs utilize CODIS with the state index administered and maintained by the MSP Crime Lab. Crime scene DNA evidence can be compared to other case samples to link cases, or to the database of convicted felon DNA profiles in an attempt to make a "cold hit" in cases without suspects. These comparisons can be made at the local, state and national level.
The "cold hit" is used as probable cause to gain a search warrant for a new DNA sample from the indicated offender. If the DNA profile generated from this new blood sample matches the crime scene/DNA profile evidence, this connection is used against the offender at trial for the offense.