Pioneer Courthouse Square during an Obama victory rally in 2008. (Creative Commons)

The FBI received a tip that Mohamed Osman Mohamud was heading down a dangerous path. It's unclear when the tip was received. They began intercepting his e-mail. When Mohamud's e-mails to a man in Pakistan who may have been a terrorist kept bouncing back, the FBI decided to pose as that man via e-mail. The FBI eventually built a fake bomb for Mohamud after he supplied them with parts for a real bomb.

Acting on Mohamud's plans and orders to create a "spectacular show" they planted the fake bomb in a car near Friday's tree light ceremony at Pioneer Courthouse Square. He didn't know it was a fake. As soon as he tried dialing on a cell phone to detonate the bomb, the FBI arrested him.

“This defendant’s chilling determination is a stark reminder that there are people — even here in Oregon — who are determined to kill Americans,” said Dwight C. Holton, the United States attorney for Oregon.

An FBI affidavit reveals Mohamud had plotted a terrorist attack since he was 15 years old, was bent on killing everyone that attended the event, found the 9/11 terrorist attacks to be "awesome" and chose Oregon because no one would ever think something bad would happen there.

He will appear in federal court on Monday and faces a maximum sentence of life in prison.

Please Note: A previous version of this story stated that Mohamud was an Oregon State University student. However, he has not attended OSU since Oct. 6 of this year.

Reach executive producer Paresh Dave here. Follow him on Twitter: @peard33.