CONNECT WITH:

By T. Christian Miller, ProPublica  FBI-seal

This story was co-published with The Atlantic.

QUANTICO, Va. — More than 30 years ago, the Federal Bureau of Investigation launched a revolutionary computer system in a bomb shelter two floors beneath the cafeteria of its national academy. Dubbed the Violent Criminal Apprehension Program, or ViCAP, it was a database designed to help catch the nation’s most violent offenders by linking together unsolved crimes. A serial rapist wielding a favorite knife in one attack might be identified when he used the same knife elsewhere. The system was rooted in the belief that some criminals’ methods were unique enough to serve as a kind of behavioral DNA — allowing identification based on how a person acted, rather than their genetic make-up.