DeKalb County state’s attorney Clay Campbell has formally requested an investigation of the Northern Illinois University Police Department and Chief Donald Grady, according to a news release Monday.

Campbell’s office has requested the investigation be led by the Illinois State Police and to focus on the mishandling of evidence in the case of former NIU police officer Andrew Rifkin. Rifkin was charged in November 2011 with with Criminal Sexual Assault (Class 1 Felony).

On Friday, Judge Robbin Stuckert said, “It is clear to me that there was a purposeful hiding of information by this department.” The statement came after Rifkin’s attorney arugued that NIU police failed to provide the DeKalb County State’s Attorney’s Office with two key witness statements in Rifkin’s case. The missing witness statements, according to a motion filed by the defense, are from two people who claim the actions between Rifkin and the alleged victim were consensual and no assault had taken place.

“We obviously cannot tolerate law enforcement agencies intentionally withholding evidence from the state’s attorney office,” Campbell said.

According to the release, the NIU police department’s actions jeopardize Rifkin’s defense and the department’s credibility.

The improper actions of the Northern Illinois University Police Department threaten not only the constitutional rights of the defendant, but also call into question any investigation conducted by this department, according to the release.