Najibullah Zazi in Aurora, Colo.

Road Trip
Two days after his second stay at the hotel, Zazi, by this time the focus of authorities' attention, rented a car and drove to New York City. After driving all night, he reached the city, stayed for two days, then flew back to Colorado, where he was arrested. It is not clear yet if he ever completed making a bomb or even determined a target. The picture "will get clearer as time goes on," an investigator said cryptically.

• An Enemy Within: The Making of Najibullah Zazi