TULSA, Oklahoma - The FBI is launching a new campaign to fight the growing problem of fake kidnapping calls.

That's when criminals lie about taking a loved one and then demand money.

The scam has been reported in Green Country.

Investigators say a lot of the calls come from criminals in Mexican prisons.

They say prisoners use smuggled cell phones to random-dial numbers in the U.S. and make their threats, then prisoners' friends or family pick up the cash sent by victims to money transfer locations.

"It's a get-rich-quick scheme where they can extort victims and have them wire money into Mexico," said Tim Ferguson of the FBI.

The FBI is focused on one group of criminals, but agents say they need the public's help to find more.

To report a call you can go to the FBI's website at www.fbi.gov.