On the morning of November 27, 2010, Portlanders woke up to disturbing news: someone, the FBI said, had tried to bomb the annual Christmas tree lighting ceremony at Pioneer Courthouse Square. According to federal law enforcement officials, the suspect, Mohamed Osman Mohamud, was arrested in a sting operation after trying to detonate a car bomb at the crowded event. Thanks to the FBI’s intervention, the bomb had no explosive components. Mohamud was arrested and charged...