DENVER (KDVR) — Decks of cards generally all look the same — there’s a suit, color and number — but the Colorado Bureau of Investigation‘s deck of cards looks a little different.

On the two of clubs, Nancy Shoupp’s face is pictured as a missing person last seen in 1990. On the 10 of clubs, there’s the unsolved murder of Kristin Titello in 2003. Next to the number and suit on one side of the card are faces and stories of Colorado’s unsolved cold cases.

Informational playing cards aren’t a new concept.

According to the Massachusetts State Police Department, playing cards in World War II were used by the U.S. military to help soldiers distinguish between planes. They were also used in 2003 to show Saddam Hussein’s members during the Iraq war. 

Based on that idea, the department said the cold case cards started in the early 2000s when cards were distributed to jails in Florida, leading to an increase in tips that eventually solved a few cases.

Now, there are decks of cards all over the country, including Colorado, featuring cold cases in the area. Here’s what a full deck looks like:

In Colorado alone, four decks have been circulating in local detention facilities, state and private prisons since 2014, according to CBI. Each of the four decks of cards features different cold cases, as there are thousands of missing and murdered people in Colorado.

While the Colorado decks are only used by people in detention facilities and prisons, CBI said that in the 10 years since the start of the deck, there have been hundreds of calls with potential tips. That being said, CBI said that the tips have yet to result in information that brought resolution to any cold cases.

While the cards haven’t solved any Colorado cases, the cards have helped cold cases across the country. According to the Florida Department of Law Enforcement, two murders have been solved with the help of a deck.