MUNCIE, Ind. (AP) – A former Ball State University math instructor has been convicted of child pornography and other charges stemming from his alleged use of a campus computer to access images of nude children.

A Delaware County judge convicted 49-year-old Brian Kenneth Siebenaler of four counts each of child exploitation and possession of child pornography Monday following a bench trial. He’ll be sentenced April 30th.

The Star Press reports Siebenaler worked at Ball State from 1992 until his May 2016 arrest. Court records say he told campus police he was viewing photos of nude boys on a campus computer shortly after the school’s commencement ceremonies ended on May 7, 2016.

Investigators say they found thousands of photos and videos of nude and semi-nude boys on Siebenaler’s office and home computers and USB drives.