SPRINGFIELD, Mo. — A former teacher’s assistant has been sentenced to 12 years in federal prison after admitting to placing a pen camera in the bathroom of a southwest Missouri elementary school.

The U.S. attorney’s office says 20-year-old Dalton Cole Sherman, of Buffalo, was sentenced Tuesday for receiving child pornography. He pleaded guilty in June to putting the small camera in the bathroom of DA Mallory Elementary School in Buffalo. School officials contacted law enforcement in 2015.

Sherman says he transferred videos from the camera to his electronic tablet to watch at home.

Investigators found videos from the pen camera and 90 images of child pornography, which was downloaded from the Internet, when they searched Sherman’s home.

Sherman faces a lifetime of supervised release after his incarceration ends.