Democratic senator defends FBI director

WASHINGTON (CNN) -- As FBI Director Robert Mueller prepares to go before a Senate committee to explain how his agency missed clues before September 11, the panel's Democratic chairman defended him Sunday.

"He's been doing everything to try to correct all the mistakes that were made leading up to September 11," Sen. Patrick Leahy told CBS' Face the Nation.

Mueller is to appear Thursday before the Judiciary Committee.

"He's the last person that should resign," Leahy said in response to critiques from some of the FBI's detractors. "There are a whole lot of people who may be culpable, who have made a whole lot of mistakes prior to that [September 11] in the Justice Department or anywhere else, but Bob Mueller's not one of them."

Leahy added, "I think the country ought to be glad he's there. I think we ought to get off his back. I think we ought to help him go forward. That doesn't mean you don't ask questions of the FBI. Of course we do."

Leahy said his questions will touch on the reorganization he announced last week that is aimed at improving the FBI's ability to analyze and share information.

"If you're simply shifting people around for the sake of shifting people around, that accomplishes nothing," Leahy said.

Attorney General John Ashcroft said Sunday the threat of terror in the United States remains, but law enforcement is improving its "capacity to understand and to anticipate and prevent" such attacks.

Asked on CNN's Late Edition with Wolf Blitzer if another terror attack could occur, he said, "Well, obviously the terrorist threat exists."

He added, "Al Qaeda wants to kill us, that's their stated purpose. They've stated it since September the 11th. So we have a real job of preventing terrorism, of taking steps to make sure that what happened before doesn't happen again."

As part of the reorganization plan, there will be more cooperation between the CIA and FBI. The CIA, for example, will send more personnel to help the FBI analyze information relating to terrorism.

Also Sunday, Mueller -- who began his job a week before the attacks -- said he welcomed a letter from a whistle-blowing FBI agent in the Minneapolis office and had no problem with any testimony she might give before congressional committees.

Leahy said Special Agent Coleen Rowley was invited to testify before his committee Thursday.

In a letter to Mueller last month, Rowley criticized the way FBI headquarters handled the investigation of suspected terrorist Zacarias Moussaoui and other probes.

"I welcome the letter. I may not agree with all that's in that letter, but I welcome the suggestions," Mueller said on NBC's Meet the Press.

In the May 21 letter, Rowley accused FBI headquarters of hindering efforts by the Minneapolis field office to learn more about Moussaoui.

Moussaoui was arrested on an immigration charge about three weeks before the deadly September 11 hijackings and had aroused suspicion at a Minnesota flight school.

FBI headquarters rebuffed the Minneapolis agent's request for a warrant to search Moussaoui's laptop computer and investigate him further. Moussaoui has since been charged as a conspirator in the September attacks.

Rowley also referred to a July 10, 2001, memo from Phoenix FBI agent Kenneth Williams, who had warned FBI headquarters of the possibility that Osama bin Laden was sending followers to U.S. flight schools in Arizona.

"I have deep concerns that a delicate and subtle shading/skewing of facts by you and others at the highest levels of FBI management has occurred and is occurring. ... I feel that certain facts ... have, up to now, been omitted, downplayed, glossed over and/or mischaracterized in an effort to avoid or minimize personal and/or institutional embarrassment on the part of the FBI," Rowley wrote in one portion of the letter.

"I recall getting the memo and looking at the memo sometime later in September," Mueller said of Williams' letter.