Reporters tried to find out what was going on at the campus police building.
"They are executing a search warrant to an ongoing criminal investigation the university is cooperating fully in this matter," said NIU spokesman Brad Hoey.
But just what "this matter" was remains a mystery.
Agents with the FBI, Illinois State Police and other federal agencies were all there. None would offer details as to what they were looking for, other than to say that public safety was never compromised. However, that statement left everyone with lots of unaswered questions.
Classes went on as scheduled. NIU students say scandal isn't anything new to campus.
"I wasn't really nervous just feeling like hey this is another thing going on at NIU nothing new always something spicy going on here," said senior journalism student Candice Beasely.
Some of that spice includes the recent firing of former NIU Police Chief Donald Grady for what a judge said was the department's blatant misconduct in a high profile rape case.
Before that NIU made news with the "Coffee Fund" scandal when faculty members were caught stealing from the school.
Investigators would not say if the search was related to either scandal, but students want to know.
"Just hoping that once they figure out what the investigation is about that htey'll let everyone know on niu campus," said Beasely.