Updated

A former teacher's assistant has pleaded guilty to receiving child pornography after admitting he placed a pen camera in the bathroom of a southwest Missouri elementary school.

Federal prosecutors say 20-year-old Dalton Cole Sherman, of Buffalo, pleaded guilty Tuesday.

Sherman admitted he put the small camera in the bathroom of DA Mallory Elementary School in Buffalo. School officials contacted law enforcement in June 2015.

Sherman said 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.

Under the plea agreement, Sherman will be sentenced to 12 years in federal prison without parole and a lifetime of supervised release following incarceration.