ALEXANDRIA, VA - A federal jury rejected the death penalty for Zacarias Moussaoui on Wednesday, deciding instead that he should be sentenced to life in prison for his role in the Sept. 11 terrorist attacks.

The verdict seemed to surprise most people in the courtroom, notably Justice Department prosecutors. They had relentlessly urged the jurors that Moussaoui, who pleaded guilty to conspiracy charges in April 2005, should be executed for his role in the deaths and destruction of the attacks.

Jurors left the courthouse without speaking about their reasoning. But court officials read aloud details of the factors jurors had voted to consider as they decided his fate, including his troubled upbringing in a dysfunctional immigrant Moroccan family in France.

The decision means that the only person charged in a U.S. courtroom in connection with the worst attack on American soil will likely spend the rest of his life in solitary confinement in a federal prison in Colorado with no possibility of release.

Moussaoui, 37, showed no reaction as Judge Leonie Brinkema received the verdict from the jury forewoman and read aloud the part that said, "We, the jury, do not unanimously find that a sentence of death should be imposed on the defendant."

Several minutes later, after the judge and jury departed, Moussaoui thrust his fists into the air in a victory gesture and shouted: "America, you lost. You lost, Novak. I won." David Novak was one of the three prosecutors who argued the case for the government.

Under the federal death penalty law, Brinkema is obliged to impose the sentence chosen by the jury. She said she would formally sentence Moussaoui on Thursday morning.

In delivering their sentence, the jurors provided partial clues to how they came to spare Moussaoui's life against the expectations of many courtroom spectators, the prosecutors and even some of his court-appointed defense lawyers. In the complicated 42-page verdict given to Brinkema, the jurors listed how many of them agreed with each of the two dozen mitigating factors put forward by the defense.

The form disclosed that two of the mitigating factors drew the greatest agreement, with nine jurors finding they were valid issues to be weighed in the decision.