CODIS

Overview

In 1990, the FBI launched a pilot program connecting DNA databases across a small group of state crime laboratories, allowing investigators to compare DNA evidence from crime scenes against profiles collected from convicted offenders across state lines for the first time. The system, which became known as CODIS, the Combined DNA Index System, expanded over the following decades into a national network now containing over 21 million DNA profiles from convicted offenders, arrestees, and forensic evidence collected at crime scenes across the country. When a detective submits a DNA sample from an unsolved case into CODIS, the system searches the entire national database for a match, linking evidence from crimes in different states, cities, and decades that investigators working independently would never have linked. CODIS has contributed to over 600,000 investigations since its inception and has been particularly transformative for cold case detectives, who can submit evidence from decades-old cases and receive matches against profiles that did not exist in any database when the crime originally occurred.

Why It Matters

CODIS fundamentally changed the geography of criminal investigation. Before it existed, a detective's ability to connect evidence to a suspect was largely limited by what was known within their own jurisdiction. Afterward, a DNA profile from a case in one state could match evidence from a case in another, linking crimes and suspects across distances that would have been invisible to any single investigator working alone. For cold case detectives in particular, CODIS represents the possibility that an investigation that went nowhere decades ago might be solved today simply because the right profile has finally been added to the database. It is one of the most powerful illustrations of how the right infrastructure, carefully built and patiently expanded over time, can change what justice can achieve.