A Kansas man has pleaded guilty to committing an Internet sex crime while he was confined as a sexual predator at the Larned State Hospital.

U.S. Attorney Barry Grissom’s office announced Monday that 38-year-old Mark David Brull and a co-defendant admitted victimizing a 14-year-old Massachusetts boy. Brull pleaded guilty to one count of the transfer of obscene materials to a minor.

Prosecutors said Brull used a phone in a common area to call a service that let him to create an email with a voice recording attachment. His co-defendant, 40-year-old Ryan J. Dancosse of Wichita, uploaded pornographic images to Brull’s accounts, which were sent to the victim.

Dancosse pleaded guilty to one count of receiving child pornography. Both men will be sentenced in October.