The man accused of masterminding thebombing of the World Trade Centerwas captured because of a $2 million dollar reward offered by the U.S. State Department, government sources tellTIME Washington correspondent Elaine Shannon. Ramzi Ahmed Yousef was arrested in Pakistan Tuesday. Today, in a New York City courtroom, he pleaded not guilty to 11 charges regarding the bombing. Sources tell Shannon that someone in Southeast Asia tipped off U.S. authorities as to Yousef's whereabouts, hoping to collect the reward. Yousef allegedly fled the United States the night of the World Trade Center bombing two years ago and has since been involved in other terrorist activity, including a failed attempt to assassinate the Pope in the Philippines. After he arrived recently in Pakistan from Thailand, police found explosives hidden inside toy cars in one of the suitcases in his Islamabad Holiday Inn room. In New York, Yousef faces a possible sentence of life in prison without the possibility of parole. He is not charged in the separate conspiracy trial currently underway, in which 11 men are accused of plotting to blow up several New York City landmarks.