Shame on FBI Director Robert Mueller for stamping “classified” on a memo from a loyal but critical agent in Minneapolis. But good for the agent, Coleen Rowley, for courageously laying out the facts of FBI’s Washington officials’ obstruction of an investigation of early signs that Osama bin Laden’s terrorists were preparing to hijack commercial jetliners and attack targets in the United States.

And good for Time magazine for somehow getting the text of the 6,000-word memo and putting it on its Web site at time.com.

And good for The New York Times’ William Safire for calling attention to the memo text and for Time magazine for its hard-hitting article this week headlined “The Bombshell Memo – How the FBI Blew the Case.”

Now the entire country can know that FBI headquarters officials repeatedly thwarted the Minneapolis agents’ efforts last August to investigate any terrorist connections of Zacarias Moussauoi, a French citizen arrested for overstaying his visa and now accused as the mysterious “20th hijacker” in the September 11 attacks. Mr. Mueller and his boss, Attorney General John Ashcroft, failed to inform President George W. Bush of advance indications of a possible impending terrorist attack.

In her memo, Agent Rowley wrote to Mr. Mueller last week: “Although I agree that it’s very doubtful that the full scope of the tragedy could have been prevented, it’s at least possible we could have gotten lucky and uncovered one or two more of the terrorists in flight training prior to September 11.” Among the details she recounted was a refusal by FBI headquarters to approve a warrant to examine Mr. Moussauoi’s laptop computer despite a French intelligence report linking him with international terrorists. Since Sept. 11, it has come out that the laptop contained the telephone number of a roommate of Mohamed Atta, the chief hijacker and pilot of one of the planes that struck the World Trade Center.

Coleen Rowley had dreamed of becoming an FBI agent since she was in the fifth grade and wrote a letter to get a booklet about the agency. She joined the FBI after obtaining a law degree in 1980 and has been chief counsel in the Minneapolis field office since 1995. She wants to keep her job and has asked to be designated a “whistle blower” under a protective law that does not ordinarily apply to the FBI.

Fear of blaming anyone for the intelligence failures that preceded the Sept. 11 attacks has gone far enough. So has the natural wartime reluctance to point out leadership mistakes. This memo provides ample evidence that the time has come for reforms that would help the future terrorist attacks widely predicted by the president on down, and such a reform would not start with an expansion of powers. It is one more reason for an investigation by a blue-ribbon commission that would be insulated from the partisan politics that can limit the effectiveness of congressional inquiries.