His sentence could turn on whether jurors believe his claims about his role in the 9/11 attacks.
Zacarias Moussaoui didn't pull the proverbial trigger of the 9/11 attacks. But was his involvement in the terror plot so extensive that he deserves to be executed?
That's a key question before the 12 jurors charged with deciding his sentence. As they weigh aggravating and mitigating factors, their answer may depend in part on how much they believe Mr. Moussaoui's own testimony about the role he played in the jetliner strikes.
Many legal analysts predict that he will receive a death sentence. And some go so far as to suggest that despite the government's sloppy and questionable tactics in the case, appeals court judges will uphold any capital sentence.
For Moussaoui, this outcome may, ironically, guarantee what he would call an exalted status - one he did not enjoy within Al Qaeda, even on the eve of the 9/11 attacks, according to his own testimony. He boasted to the jury that he was assigned to fly a jetliner into the White House - an objective that would have been the terror group's most important target on that day. Yet he also admitted that he was on a kind of probation within the terror group at the time. So why would Al Qaeda trust such an important objective to someone the plot masterminds considered unreliable?
Some say perhaps Moussaoui was playing a game with the US Justice Department when he took the stand and admitted involvement in 9/11 after having repeatedly denied it. He wants to become a martyr, they suggest.
But there is a problem.
Many terrorism experts question the veracity of Moussaoui's testimony. They say the evidence suggests he was training for a second wave of attacks after 9/11, not the 9/11 attack itself.