(MCT) — The DeKalb County state’s attorney has asked state police to investigate the Northern Illinois University police department and its police chief after a judge ruled last week the department hid evidence that could have cleared one of its officers of a felony sexual assault charge.

Officer Andrew Rifkin was charged with criminal sexual assault in November 2011 after he allegedly attacked a NIU student, according to a news release. He was later fired from the job after an investigation, the release stated.