UPDATE: November 17 at 5:30 p.m.
Now, the investigation switches to, who left written bomb threats on the WIU campus.
The FBI says they have the man responsible for all of the phoned in bomb threats.
But more than likely are looking for a second person who wrote the letters.
The FBI is taking a close look at those letters.
"There were three notes that were left on campus and we recovered those notes. We will continue to investigate this matter and examine notes for evidence."
University of Relations Director Darcie Schinberger says the third note was not a bomb threat. But directed at a residence assistant at Higgins Hall.
So far, agents have arrested WIU student Cameron McKoy on federal charges in connection with all of the phoned threats.
Click here to read the official criminal complaint filed by Special Agent Mark T. Hill, FBI.
UPDATE: November 16 at 5:30 p.m.
The FBI says they believe a Western Illinois University student is responsible for a string of bomb threats on campus. Agents arrested 18-year-old Cameron McKoy earlier today in Chicago on federal charges.
Click here to read the Department of Justice official document.
He's the same man arrested for the first bomb threat at WIU, called in on October 25.
Special Agent Stu McArthur says the FBI believes McKoy used robo-calls to make all of the phoned-in bomb threats. They were able to trace the IP address of the calls to a "WIU HACKER" Facebook account. That account was registered to a relative of McKoy. The FBI does not believe the family member is involved in any way. McKoy is charged with making a bomb threat by phone.
Cameron McKoy of Chicago will make an initial appearance in the United States District Court in Peoria Tuesday afternoon.
More information about the charge will be available after McKoy's court appearance.
The 18-year-old was arrested earlier Tuesday in Chicago.
Western Illinois University students have been through six bomb threat scares in the past several weeks.