When traditional leads run out, cold-case detectives sometimes rely on a what seems like a flippant way to deal with homicides and missing-persons cases: card games. 

Inspired by the “personality identification playing cards" used by the U.S. government in 2003 to help identify the most-wanted members of Saddam Hussein’s government, some states print decks of cards featuring the names and images of victims of unsolved crimes. These cold-case playing cards are designed to jog the memories of the inmates who use them, potentially leading to useful tips for investigators.

Where a normal deck of playing cards might have an icon reflecting the suit, or an image of a king or queen, cold-case playing cards typically feature the portraits and names of victims with a short description of the crime, and any reward offered. Versions of them are distributed in prisons in more than a dozen states, including Florida, New York, South Carolina, Idaho, and Colorado, among others. The idea has also been exported internationally, to Australia.

The idea is that as inmates play a game of poker or hearts, they might see a description of a crime they recognize—something they’ve maybe heard a fellow prisoner boast about, for instance. They can then make a free phone call to a cold-case hotline. Several states have printed multiple editions of the card decks, updating them with new cases.

While there isn’t national data available on the success of these programs, at least a few cases have been closed thanks to cold-case card programs. In 2007, a game of Go Fish in a Florida prison led to a tip that solved a three-year-old murder. A total of nine Connecticut cold cases have been solved as a result of the playing card program, Chief State’s Attorney Kevin Kane told Slate. As of April 2015, the Colorado Bureau of Investigation has received more than 60 tips from inmates using the cards.

States vary in how they pay for the playing card programs. Some sell the cards to inmates, while others are funded by grants or the state corrections department’s budget.

They may not be the most glamorous or upbeat playing cards ever designed, but they have led to the most useful game of Go Fish ever played.

[h/t: Slate]