A registered sex offender who sent obscene material while he was a patient at Larned State Hospital has been sentenced to 20 years in federal prison.

U.S. Attorney Barry Grissom announced that 34-year-old Christopher Case was sentenced Monday to transferring the material.

Prosecutors say Case used a cell phone to send an obscene video to a 13-year-old girl in Montana in January 2012. He was a patient of the state’s sexual treatment program at the time.

Case’s original crimes were committed in Saline and Dickinson counties and date back to 2002. He was convicted of attempted aggravated indecent solicitation of a child in connection with a 2002 arrest in Saline County and aggravated endangerment of a child in connection with a 2006 arrest in Dickinson County.