Agent Coleen Rowley wrote that the Minnesota agents became so frustrated by roadblocks erected by terrorism supervisors in Washington that they began to joke that FBI headquarters was becoming an "unwitting accomplice" to Osama bin Laden's efforts to attack the United States, the officials said.
As new details emerged about the letter Rowley wrote to FBI Director Robert Mueller, key members of Congress sought to extend her whistle-blower protections and encouraged more agents to come forward.
A joint panel of House and Senate members set the first hearings to examine what the government knew before Sept. 11 about terrorist threats and what mistakes it made.
"This (Rowley) letter documents exactly what headquarters knew and when, and how midlevel officials sabotaged the Moussaoui case before the attacks," Sen. Charles Grassley said Friday.
Officials familiar with Rowley's memo said she alleged that FBI headquarters terrorism supervisors rewrote the Minnesota office's warrant applications and affidavit and removed intelligence about Moussaoui before sending them to a legal office that then rejected them as insufficient.
She alleged that some of the revisions "downplayed" the significance of some intelligence linking Moussaoui to Islamic extremists, and blamed the changes on a flawed communication process.
"Obviously, verbal presentations are far more susceptible to mischaracterization or error," Rowley wrote in her 13-page letter, excerpts of which were obtained by The Associated Press.
The Minnesota office was concerned after arresting Moussaoui at a Minnesota flight school in August 2001 that he was seeking to hurt Americans and wanted to gather more information through national security and search warrants, including getting information off his computer.
Some of that information came from an associate of Moussaoui who told the FBI the flight student held extreme anti-American views. Other intelligence came from France linking Moussaoui to radical Islamic extremists in the region although not directly to al-Qaeda, officials said.
The officials, who spoke only on condition of anonymity, said Rowley identified the warrant revision process as flawed, particularly complaining that Minnesota was never consulted about the changes that were made before the warrant applications were forwarded to the offices that rejected them.
Officials said Rowley in other parts of the memo attacked the public explanations that Mueller and other FBI senior officials have offered about why the FBI failed to connect the dots before Sept. 11.
Rowley wrote she had come to the "sad realization" that officials had skewed facts in the post-Sept. 11 accounts and were trying to "circle the wagons" to protect FBI headquarters from embarrassing disclosures.
She also criticized the culture of Washington headquarters, saying FBI higher-ups were too concerned with "petty politics" and too afraid to make tough decisions that could affect their career ascensions, the officials said.
"There were statements indicating that she felt that the higher-echelon leadership in the FBI had had a pattern of submerging what they considered to be critical comment,'' Senate Intelligence Committee Chairman Bob Graham said.
Graham said the letter, which has been classified secret by the FBI in eight places, was "very serious" and that he anticipated investigators would look at the cultures inside the intelligence agencies.
Grassley, a member of the Senate Judiciary Committee, said Rowley's letter alarmed him.
"If FBI headquarters is still handling terrorism information like it handled the Moussaoui case, we're in grave danger. This was worse than dropping the ball," he said in a statement urging the FBI to declassify the letter.
Several times, Rowley complained in the letter that Minnesota had never been told of a separate memo written in July by a Phoenix FBI agent warning that Arab pilots in Arizona with ties to radical Muslims were training at flight schools.
FBI officials have repeatedly said the agency failed to connect the two matters before Sept. 11.
CBS News Correspondent Jim Stewart reports the FBI confirmed Friday that for a critical period stretching from the middle of July, when the first warning memo appeared, to just before Sept. 11, the FBI unit responsible for tracking Osama bin Laden did not have a permanent unit chief.
Rowley emerged as a central figure this week after authoring a letter Tuesday to Mueller and senators alleging FBI headquarters erected a "roadblock" to the efforts to prove before Sept. 11 that Moussaoui was a terrorist.
After the attacks, Moussaoui was charged as the lone accomplice so far to bin Laden and the hijackers.
Graham and Rep. Porter Goss, chairman of the House Intelligence Committee, who are heading Congress' inquiry into U.S. intelligence and the attacks, said their first hearing will take place June 4 but will be closed to the public so they can discuss classified intelligence sources.
The committees' investigation is examining the U.S. intelligence response to terrorism since 1985, as well as looking into specific information that might have pointed to the Sept. 11 attacks.