MASSACHUSETTS · FINGERPRINT ERROR · WRONGFUL CONVICTION

A mistaken fingerprint identification helped send Stephan Cowans to prison for nearly six years.

Latent print testimony + eyewitness identification → conviction → DNA exclusion → fingerprint error exposed

Stephan Cowans was convicted in 1998 of offenses arising from the shooting of a Boston police officer. At trial, Boston Police fingerprint analysts testified that a latent thumbprint recovered from a water mug at the crime scene belonged to Cowans. Eyewitness identifications also implicated him.

Post-conviction DNA testing later excluded Cowans from the hat, sweatshirt and mug associated with the perpetrator. The fingerprint evidence was reexamined as well, and officials concluded that the latent print had been wrongly individualized to Cowans. Prosecutors dismissed the charges in 2004. Cowans had spent about five and a half years in prison.

The Boston Police Department subsequently shut down its latent fingerprint unit temporarily and investigated the analysts involved.

Why it matters: Biometrics are often treated as stronger than eyewitness testimony. Cowans shows that a mistaken biometric identification can reinforce other weak evidence and make a wrongful case look more certain than it is.

Sources: Innocence Project case record · Massachusetts Supreme Judicial Court discussion

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