Finding Shahzad

Peter Baker and Scott Shane have an article in The New York Times about locating Faisal Shahzad:

Investigators discovered the name of the suspect in the failed Times Square bombing because of a telephone number he provided when he returned to the United States from Pakistan in February, a law enforcement official said. The phone number he gave three months ago was entered in a Customs and Border Protection agency database, and came up Monday when investigators were checking the record of calls made to or from the prepaid cellular telephone used by the purchaser— at that point unidentified— of the vehicle used in the failed bombing, the official said. Only when they matched the phone number did investigators learn that “that was the guy we were looking for,” said the official, who spoke on condition of anonymity.
The phone-record link underscored the combination of investigative skill, increased government integration, and sheer luck that helped authorities track down Faisal Shahzad just 53 hours after a vehicle packed with explosives was parked in the heart of Manhattan. Once investigators had Mr. Shahzad’s identity, they were able to put his name on a no-fly list that ultimately led to his being pulled off a plane about to leave the country.
Mr. Shahzad, 30, a Pakistani-American who was naturalized as a United States citizen last year, has been charged with terrorism-related crimes and has waived his right to a speedy arraignment, officials said, meaning that he does not have to be brought to court right away. The government has said Mr. Shahzad admitted receiving bomb-making training in the tribal regions of Pakistan and then driving the car bomb into Times Square over the weekend.
The latest details about how investigators tracked him down add to a detective story worthy of a Hollywood movie. When New York police were alerted to the presence of the smoking Nissan Pathfinder and rendered it safe on Saturday night, they started out without any immediate suspects. The owner had evidently taken steps to avoid being identified, buying the vehicle with cash, and apparently removing the visible vehicle identification number.
But, after the police found the vehicle number on a hidden part of the engine, they tracked down the Connecticut woman who had sold it. While she did not remember the buyer’s name, and had no paperwork from the sale, she did have the number of the phone he had used to contact her. That number led to a prepaid cellphone with no registered owner.
The authorities have said that phone received four calls from Pakistan in the hours before he bought the 17-year-old sport utility vehicle for $1,300. When they ran all the numbers tied to that phone through government databases, the only match they got was the number Mr. Shahzad had given when he returned to the United States on 3 February on an Emirates flight.
Because he was coming from Pakistan, Mr. Shahzad was pulled aside for secondary screening upon arrival, the authorities said. After a Nigerian man tried to blow up a Northwest Airlines flight bound for Detroit on 25 December, the federal government mandated additional screening for all passengers arriving from fourteen mostly Muslim countries, including Pakistan. That program has since been dropped in favor of a more selective screening system.
Mr. Shahzad was questioned by Customs and Border Protection agents, who in such sessions typically ask where the passenger has been, why he was there, whom he saw, and so forth. As part of that process, a report was generated on Mr. Shahzad, including all passenger data and at least one phone number that he provided. It was not clear whether the number was the emergency contact number he had given the airline, or one that he provided to agents during questioning.
Either way, Customs and Border Protection passed along the data to the Federal Bureau of Investigation, which put it in its own database. Three months later, when FBI agents checked the numbers tied to the prepaid telephone, the Customs and Border Protection report came up. The FBI then contacted the agency for more information about Mr. Shahzad.