Mr. Moussaoui's Confession

His testimony confirms the government's case. But is it true?

GIVE ZACARIAS Moussaoui credit: Years into his bizarre circus of a trial -- after all his deranged court filings and speeches, his pleas and retracted pleas, his attempts to act as his own lawyer and his denunciations of his long-suffering court-appointed lawyers -- he still knows how to grab a big moment and milk it. This week, he took the witness stand and confessed -- "boasted" might be a better word -- that he was, as the government alleged, a part of the Sept. 11 conspiracy and that he was meant to fly a fifth plane into the White House, along with convicted "shoe bomber" Richard Reid, as part of the coordinated attacks that took place that day.

Mr. Moussaoui's riveting testimony devastates his defense and acknowledges everything prosecutors need to prove and then some.

Not only did he lie to the FBI to protect the operation after his capture the month before the attacks -- the allegation to which he admitted last year. He also bought a radio to hear news of the operation's success. He knew that the World Trade Center was a target. He coldly described his delight at learning of the destruction and carnage. After such a display, what jury could fail to vote for the death penalty?

But there is reason to worry that Mr. Moussaoui's testimony is a bit more dramatic than the reality of his involvement. For one thing, it contradicts his own prior statements: He has claimed in the past not to have been involved in Sept. 11 but to have been preparing for a separate attack on the White House. It also contradicts the statements of al-Qaeda bigwigs in U.S. custody, which -- in a bizarre twist -- the defense put before the jury in an effort to discredit its own client. Khalid Sheik Mohammed, for example, claimed that Mr. Moussaoui was sent here as part of a second wave of strikes. It even exceeds what the government itself has alleged.

The government and Mr. Moussaoui, at this point, are both pushing for his execution -- as vividly illustrated by his bizarre offer to testify for the prosecution. Their motives differ. The government is prosecuting his crime, while Mr. Moussaoui appears to be attempting to martyr himself. The danger is that in such a confluence of interests the truth falls by the wayside.

That would be dangerous, in part because the government's theory under which Mr. Moussaoui is eligible for death is an expansive one that could open the door for executions of low-level conspirators in a range of criminal enterprises. Mr. Moussaoui without question acted as an al-Qaeda operative who arrived in this country intending to do it great harm. Less clear is what role, if any, he played specifically in the events of Sept. 11. That he now wishes to claim a big one may imply honest pride in his work or simply a desire to die for his organization's greatest success -- a desire no jury ought to oblige. The unenviable task of the jurors, who now have the case, will be to sort true confession from idle boasting.