The sixth threat took place late Thursday. A note was found in Higgins Hall dormitory on the campus in Macomb, Ill. Police searched the building.
The first threat was on October 25. An 18-year-old Chicagoan was arrested in that case and is awaiting trial.
School officials have now established a stop the threat fund to help track down the suspect. They have also increased security by hiring extra officers and having the Illinois State Police patrol campus. Also, officers are assigned to dorms 24 hours a day.