LINCOLN, Neb. (AP) — An Omaha man has been convicted of attacking an employee at the state prison intake center for male prisoners.

25-year-old Justin Gardner was found guilty Tuesday of assault. His sentencing is scheduled for Dec. 19.

Authorities say Gardner went to a prison lieutenant’s office at the Diagnostic and Evaluation Center in Lincoln on Nov 17, insisting that he’d finished his sentence and should be released. The incident ended soon after Gardner got angry and punched the lieutenant in the face.