SIOUX FALLS, S.D. (KELO) — A former South Dakota teacher has pleaded not guilty of having child pornography.

Before his arrest, 33-year-old Charles Reambonanza was a science teacher at St. Francis Indian School.

According to court documents, he told federal investigators that he’d been watching child pornography for several years, and admitted having illegal images on several devices.

The school suspended him immediately after learning about the allegations.