SAN JUAN, Puerto Rico (AP) — The FBI says charges have been filed against a Puerto Rican inmate for making what it asserts were death threats against the island's U.S. attorney.

A Monday statement from the FBI's San Juan division alleges that Jose Villafane Cotto wrote a letter to U.S. Attorney Rosa Emilia Rodriguez saying she should announce her resignation or she would "pay with her life."

The suspect allegedly sent the letter from the Puerto Rican lockup where he was jailed. The FBI also alleges he called their San Juan office to repeat the same threats against Rodriguez.

If convicted of mailing a threatening communication and threatening a federal official, Villafane faces up to 15 years in prison. It was not immediately clear if he had a lawyer or why he was behind bars in the first place.