LINCOLN -- The Sigma Nu fraternity on the UNL campus has been "red tagged", meaning the building is not safe for people to be inside. Fire inspectors went into the fraternity Sunday afternoon at 625 North 16th on a fire call and found piles of garbage...so much it was reportedly blocking hallways. They found smoke detectors and fire alarm warning devices removed or tampered with and several other smaller violations. University Police Sergeant Zach Byers said their office is investigating whether any criminal activity may have occurred. Inspectors say until their office is satisfied about safe operations of the building's fire systems, no one will be able to occupy the building. Sigma Nu only passed inspection last summer after after the building had been condemned. With Monday being a holiday, the 50 or so displaced residents will have to remain outside the fraternity until Fire Inspectors conduct an inspection on Tuesday.