He knew. He lied. 2,749 people died.

He knew. He lied. 2,749 people died.

Zacarias Moussaoui settled his worthiness for execution yesterday when he testified that he had signed on with Al Qaeda to help fly a fifth hijacked airliner on 9/11, intending to deepen America's wounds by crashing it into the White House.

By admitting for the first time that he and would-be shoe bomber Richard Reid were part of a 9/11 conspiracy larger than previously known, Moussaoui revealed himself as a material participant in the worst attack on American soil. That the happenstance of an immigration arrest kept Moussaoui grounded in no way lessens his culpability or the appropriateness of capital punishment.

Moussaoui enlisted in Osama Bin Laden's army not to wage war according to international norms, but to perpetrate crimes against humanity for which Bin Laden and all his lieutenants would be fit targets of execution - summary execution, should the military stumble upon them under the right circumstances. We should be so lucky.

There are those who say Moussaoui is unreliable in that he previously confessed only (only!) to plotting to destroy the White House on a date other than 9/11. We are prepared to credit his account, noting particularly his admission that he deceived investigators about his true purpose in August 2001 because he wanted the attack on the World Trade Center to proceed.

"I had knowledge that the twin towers would be hit," the 20th hijacker testified matter-of-factly.

He knew.

He lied.

And 2,749 people died.

Because Moussaoui's fate is being decided by a civilian jury - as opposed to a military tribunal - this last admission may be the most critical. Under the strictures of criminal law, federal prosecutors have the burden of proving that Moussaoui could have prevented the 9/11 attacks by warning the FBI about the plot when agents questioned him. Without such proof, he gets life without parole.

Now, Moussaoui's lawyers are trying to convince jurors the U.S. was so inept pre-9/11 that nothing he might have said would have made a difference. While the government's failures were many, lapses by the FBI, CIA and others before the world grasped the scope of Al Qaeda's intentions in no way alter the fact that Moussaoui was, and is, a determined enemy of the U.S. who set out to attack a seat of American democracy, the White House, on 9/11 or thereafter.

At this point, we can only rue that military justice was not brought to bear on an illegal combatant who abetted an atrocity - and pray that the jury grasps three truths:

He knew.

He lied.

And 2,749 people died.