Alleged bomber left an electronic trail

A traceable electronic trail, spread by a disposable cell phone and email, was key in finding Faisal Shahzad, the man allegedly behind the attempted Times Square car bomb.

Shahzad was arrested May 3 as he tried to leave the United States on a commercial flight to Dubai. According to the criminal complaint against him, Shahzad admitted attempting to detonate an explosion from inside his parked Nissan Pathfinder on the evening of May 1, and to having received bomb-making training in Waziristan, Pakistan.

According to news reports and the complaint, the identity of the would-be bomber was found after investigators traced the Pathfinder's previous owner through a vehicle identification number found on the Pathfinder's engine block. Shahzad bought the vehicle for $1,300, in cash, on April 24.

The previous owner, identified in news reports as Peggy Colas, 19, of Bridgeport, Conn., had advertised the Nissan for sale through various websites, including Craigslist.org. Shahzad emailed Colas through that site, according to the Hartford Courant. Craigslist allows sellers to anonymize email addresses, but not buyers.

Shahzad also used a prepaid Verizon Wireless cell phone to call Colas, according to the complaint. That same phone received four calls from a number in Pakistan associated with Shahzad, the complaint states, and Shahzad used the disposable phone to contact a Pennsylvania store that sells the type of fireworks used in the attempted car bomb.

Shahzad, a Pakistani-born naturalized U.S. citizen, had lived in Connecticut, returning there in February following what Shahzad said at the time was a five month visit to Pakistan, where his parents live, according to the complaint.

Customs and Border Patrol placed Shahzad on the No Fly List May 3, said FBI Assistant Director John Pistole during a May 4 press conference. How Shahzad was able to get on Emirates airlines flight EK202 is unknown; the Associated Press and the New York Times write that Shahzad evaded federal surveillance and that Emirates officials didn't check for new additions to the list. The Christian Science Monitor considers the possibility that Shahzad was permitted to board his flight, so officials could see if he was meeting someone onboard.

Less clear in the record of the investigation is how useful video surveillance was. Investigators initially searched for man caught on camera in Times Square standing next to the Nissan Pathfinder and changing his shirt before the vehicle began to smoke. But that man now appears to have been a mere bystander.

But, as William Saletan of Slate.com notes, a video camera in the parking lot where Shahzad test drove the Nissan Pathfinder before buying it showed an image of attempted bomber.

"Terrorists, take note: If Big Brother isn't watching you, somebody else's camera probably is. We just have to find it," Saletan adds.

For more:
- see the criminal complaint against Shahzad
- listen to audio of Emirates flight EK202 being recalled back to the gate after CBP officials identified Shahzad as a passenger
- read a transcript of a May 4 press conference with Attorney General Eric Holder and DHS Secretary Janet Napolitano on the Shahzad arrest
- see an official version of Holder's press conference statement