FBI's 9/11 Team Still Hard at Work

A few members are not FBI agents. Robert F. Sassok, 43, a New York City police detective, gave up a lucrative pension to work on PENTTBOM. As a member of New York's joint terrorism task force, he had previously worked on the case of the 1998 U.S. Embassy bombings in Africa.

"We hoped we'd put a dent in them," Sassok said of the earlier case. "But the way they operate, we couldn't be sure. . . . You felt a sense of satisfaction putting people away in the embassy bombings. Then you think, here we go again."

The Evidence

The list hangs from a divider in the team's basement redoubt, nearly five feet long. In Project Backtrack, FBI investigators drew upon millions of passenger records turned over voluntarily by airlines to tally more than 180 flights taken by the 19 hijackers since 1991.

They include surveillance flights in the United States in the summer of 2001. Six hijackers, at least one from each plane, took the practice flights in the United States between May and August 2001, the PENTTBOM team has concluded. All went from the East Coast to California and back, and each made a stop in Las Vegas. On at least one leg, the traveler occupied a seat near the one he would take on the day of the attacks.

From the broader universe of all hijacker flights, the team has also identified the "dirty 44," names that appeared on the same 180 flight manifests more than once. In many cases, however, authorities cannot tell whether the individuals are the same because of spelling differences and a lack of personal information, and few answers have been gleaned from the mysterious list, investigators said.

The team has logged more than 155,000 items of evidence, including debris from the attack and crash sites. Investigators also assembled a timeline more than 8,000 lines long of the hijackers' activities in the United States. Pasquale "Pat" D'Amuro, a former FBI counterterrorism chief and head of the New York field office, calls the list "one of the most significant things the investigation did" because it serves as the primary framework for understanding how the plot was organized and why it was successful.

The linchpins of the probe are bank and telephone records, which allowed PENTTBOM investigators to rapidly reconstruct the activities of the hijackers and their associates, and to continue tracking al Qaeda movements to this day.

The team has played a central role in the aggressive tactics used since the attacks to monitor and apprehend suspected al Qaeda associates, including would-be hijackers such as Hamlan, who is in custody in Saudi Arabia.

Another probable hijacker identified by the team, Mohamed Qahtani, was foiled in his attempt to enter the United States a month before the attacks. Qahtani, a Saudi national whose existence was first revealed earlier this year by the Sept. 11 commission, had been picked up in Afghanistan and was being held in Guantanamo Bay in the summer of 2002 when authorities got a hit on his fingerprints. He had attempted to enter the United States at Orlando on Aug. 4, 2001.

PENTTBOM investigators, aware that Atta was in Central Florida about the same time, manually searched parking and telephone records and determined that Atta was on a payphone in the Orlando airport at the same time Qahtani was detained for questioning by a suspicious immigration inspector. The call was made to a phone used by Mustafa Ahmed Hawsawi, the alleged paymaster in the terrorism plot.

Qahtani, the team concluded, was meant to be part of the hijacking plot, foiled only because the inspector refused to grant him entry. The discovery prompted a mobilization of field agents to search for other accomplices. They sifted by hand through months of parking receipts at eight major airports and compared them with license plates of cars the hijackers used.

"At every [U.S.] airport that we knew a hijacker had been to, we went through the same exercise," Galligan said. But no additional matches were found.

The PENTTBOM team also played a leading role in the 20-month investigation of Bradley University graduate Ali Saleh Kahlah Marri, who was put in a military brig in June 2003 after President Bush accused him of being an al Qaeda sleeper agent. PENTTBOM and Illinois FBI agents surveilled Marri in the months after the terrorist attacks after discovering that he had called a United Arab Emirates phone number associated with Hawsawi.

Marri was arrested as a material witness in late 2001. Khalid Sheik Mohammed, the mastermind of the attacks who was apprehended in Pakistan in March 2003, has told U.S. authorities that Marri was an al Qaeda agent, said sources familiar with the interrogations, leading to Marri's designation as an enemy combatant.