Darren Mitchell, NIU’s deputy police chief, has been placed on paid administrative leave as the Illinois state police investigate a potential “discrepancy” in his work.

NIU Police Chief Tom Phillips said he “came across some discrepancies” late last week and spoke with Bill Nicklas, vice president of Public Safety and Community Relations, Monday morning. Mitchell was then placed on paid administrative leave.

Phillips said he reached out to the state police to investigate for “transparency and objectivity.”

“[I thought the] best measure to move forward was to have an internal investigation,” Phillips said.

Phillips said the alleged discrepancy was only related to one instance, but declined to comment as to what instance that was.

Nicklas said the state investigation would be “deliberate and thorough.”

“I think it’s important to have an independent investigation,” Nicklas said.

Phillips said he had no timeline as to when Mitchell may return or when the investigation would be over. Mitchell was making about $140,000 and his duties entailed overseeing officers who worked in residence halls, training and emergency planning.

Mitchell was selected as acting police chief when Don Grady, NIU’s former police chief, was placed on paid leave in November 2012 and then fired in February 2013. He continued in that role until Phillips started in September.

NIU police have seen other issues in recent years: The FBI is still investigating the department, and Grady was fired after the department allegedly mishandled an investigation into a student’s claim that former NIU officer Andrew Rifkin sexually assaulted her. Grady and Rifkin sued NIU following their dismissals.

Mitchell and a state police spokesperson did not respond to messages asking for comment.