But 19 months later, the commission released a final, unanimous report on Thursday that, in calling for an overhaul of the way the government collects and shares intelligence, showed that much of what had been common wisdom about the attacks at the start of the panel's investigation was wrong.

In meticulous detail, the 567-page report rewrote the history of Sept. 11, 2001, correcting the record in ways large and small and shattering myths that might otherwise have been accepted as truth for generations.

The report found that the hijackers repeatedly broke the law in entering the United States, that bin Laden may have micromanaged the attacks but did not pay for them, that intelligence agencies had considered the threat of suicide hijackings, and that Bush received an August 2001 briefing on evidence of continuing domestic terrorist threats from al-Qaeda.

"Our work, we believe, is the definitive work on 9/11," said Thomas H. Kean, the former Republican governor of New Jersey who led the panel, and whose consensus-building talents are credited by other commissioners as the reason the report was unanimous. If there are unanswered questions, Kean said, it is mostly because "the people who were at the heart of the plot are dead."

The hijackers. For the commission of five Democrats and five Republicans, the work of correcting the record began with an understanding of how 19 Arab terrorists managed to enter the United States unnoticed, hiding in plain sight in the weeks and months before they acted to kill more than 2,700 people.

This was the subject of the first of what would be a series of riveting public hearings held by the commission this year. The first hearing in January showed just how wrong - and self-serving - much of the government's information about the Sept. 11 plot had been. And it suggested just how aggressive the commission intended to be in setting the record straight.

In the months that followed Sept. 11, the FBI, the CIA and other agencies defended their failure to detect the plot by insisting the hijackers had gone out of their way to enter the country legally and to avoid detection once inside.

"Each of the hijackers, apparently purposely selected to avoid notice, came easily and lawfully from abroad," Louis J. Freeh, former FBI director, testified to Congress in October 2002. "While here, the hijackers effectively operated without suspicion, triggering nothing that alerted law enforcement."

But in its final report, the commission found that as many as 13 hijackers had entered the country with passports that had been fraudulently altered, using criminal methods previously associated with al-Qaeda.

Imagining the unimaginable. In trying to explain why the nation had left itself so vulnerable on Sept. 11, the leaders of U.S. law enforcement and intelligence agencies have insisted that they never considered the nightmare of passenger planes turned into guided missiles.

"I don't think anybody could have predicted that these people would take an airplane and slam it into the World Trade Center," Condoleezza Rice, Bush's national security adviser, said in May 2002. As recently as April, Freeh told the Sept. 11 commission that he "never was aware of a plan that contemplated commercial airliners being used as weapons."

But in its investigation, the commission found that an attack described as unimaginable had in fact been imagined, repeatedly. The commission said that several threat reports circulated within the government in the late 1990s raised the explicit possibility of an attack using airliners as missiles.

Bin Laden's role. U.S. intelligence agencies had known for years that the United States had much to fear from bin Laden, but that fear was based more on his power as a global symbol of Islamic fundamentalist rage than as a terrorist logistician. A senior State Department official told the Senate in 2001 that bin Laden's terrorist network was "analogous to a multinational corporation, bin Laden as CEO," leaving the details of the attacks to others.

But the commission found that far from being a disengaged leader, bin Laden was described by captured colleagues as a hands-on executive who wanted to be involved in almost every detail of the Sept. 11 plot, choosing the hijackers himself and selecting targets. He was reported to have been eager to hit the White House.

U.S. intelligence analysts had long believed that bin Laden had a vast personal fortune that bankrolled al-Qaeda; news accounts described it as totaling as much as $300 million.

But the commission found that he had been cut off from his family's wealth after the early 1990s and that he financed al-Qaeda's operations through wealthy Muslim donors, mainly in the Persian Gulf. The report said that from 1970 to 1994, he received about $1 million a year from family funds - not nearly enough to finance such an ambitious terrorist network.

The evidence. In the first hours after the Sept. 11 attacks and ever since, the White House has consistently insisted that Bush and his deputies had no credible evidence before the attacks to suggest that al-Qaeda was about to strike on U.S. soil.

But the assertion has been questioned as a result of the commission's digging. After its most heated showdown with the administration over access to classified information, the commission pressured the White House to declassify and make public a special intelligence briefing that had been presented to Bush at his Texas ranch on Aug. 6, 2001.

The document's existence - but not its contents - had been known about since 2002, when the White House confirmed news reports that Bush had received an intelligence report before Sept. 11 warning of the possibility that al-Qaeda might hijack passenger planes.

In testimony in April to the commission, before it was made public, Rice insisted that the report was "historical."

"It did not, in fact, warn of attacks inside the United States," she testified. "It was historical information based on old reporting. There was no new threat information."

But there were gasps in the hearing room when she disclosed the title of the briefing paper: "Bin Laden Determined to Attack in U.S."

The document was made public several days later and contained passages referring to FBI reports of "suspicious activity in this country consistent with preparations for hijackings or other types of attacks, including recent surveillance of federal buildings in New York." It noted that a caller to the U.S. Embassy in the United Arab Emirates that May had warned that "a group of bin Laden supporters was in the U.S.," planning attacks with explosives.

The commission's final report revealed that two CIA analysts involved in preparing the brief had wanted to make clear to Bush that, far from being only a historical threat, the threat that al-Qaeda would strike on U.S. soil was "both current and serious."

http://www.philly.com/mld/inquirer/news/nation/9235118.htm?1c