ALEXANDRIA, VA. -- Unable to reach consensus on a death penalty in the nation's only Sept. 11-related criminal case, a federal jury sentenced Zacarias Moussaoui on Wednesday to life in prison without the possibility of release.

Jurors found unanimously that Moussaoui's crime met the legal threshold for execution, but at least one and possibly several jurors gave even more weight to factors such as his apparently limited role in the terror plot and his troubled upbringing.

Coming more than 4½ years after Moussaoui was arrested in the Twin Cities, the verdict was delivered after 41 hours of deliberations over seven days. It ended a three-month penalty trial in which the government invested massive resources to try to prove that Moussaoui's lies to federal agents contributed to the carnage on Sept. 11, 2001.

The complicated, 42-page verdict form showed that the jury unanimously agreed Moussaoui's crime could have deserved the death penalty. But some jurors gave weight to mitigating factors.

Three found that Moussaoui had "limited knowledge" of the Sept. 11 plot, three said he was a minor player and six to nine factored his troubled childhood and abusive father in his favor. Four jurors gave weight to psychotic disorders suffered by his two sisters and father -- an indication that they also question Moussaoui's mental stability, and three said they took into account that he was subjected to racism as a Moroccan growing up in southern France.

Mitigating factors

None of the jurors mentioned Moussaoui's desire for martyrdom as a mitigating factor, but it was not clear whether the verdict was influenced by any jurors' desire to prevent him from dying an Al-Qaida hero.

It was not clear how many of the jurors held out for a life sentence, a detail that might remain secret. The jurors have been kept anonymous and were whisked to their cars by deputy U.S. marshals after the verdict.

As U.S. District Judge Leonie Brinkema read the verdict in a hushed courtroom, Moussaoui appeared as taken aback as many of the spectators, including several relatives of victims of the nation's worst terrorist attack. On April 3, the same jury found unanimously that he was eligible for the death penalty, just days after he boasted to the jury that he was part of the Sept. 11 plot and wanted to kill as many Americans as possible.

Moussaoui, who also admitted that he lied to federal agents in Minnesota to conceal the suicide hijacking scheme, sat motionless, slumped in his chair. But as the jurors departed, he slowly broke into a broad smile and flashed a "V" for victory sign.

Then, as he was taken from the courtroom, he clapped his hands and shouted: "America, you lost!" and that prosecutors David Raskin and David Novak had lost. "I won!" he said.

The jury's decision culminated an emotion-wracked trial that reexamined the nation's deadliest crime and shed new light on the failure of federal agencies to prevent it. The suicide hijackings, in which terrorists piloted jetliners into the World Trade Center and the Pentagon, set off the United States' global war on terrorism.

In a statement, President Bush noted that Moussaoui pleaded guilty a year ago to conspiring "to murder innocent Americans" and "openly rejoiced in their deaths."

"This afternoon, the jurors ... concluded that this man should spend the rest of his life in prison," he said. "Our thoughts today are with the families who lost loved ones on September 11th, 2001. Our nation continues to grieve for the men, women and children who suffered and died that day."

Unanimity elusive

The weary-looking jurors, led by a female mathematics teacher, found that eight of the government's 10 proposed aggravating factors fit his crime. To meet the threshold for imposing the death penalty, they had to make that finding for at least one of the three most serious aggravating factors and they did so on two: That the crime threatened people in addition to those killed on Sept. 11 and that it involved substantial planning and premeditation.

But on none of the three capital conspiracy counts did they find unanimously, and beyond a reasonable doubt, that his crime was carried out in a "heinous, cruel or depraved manner" involving torture or physical abuse. They also did not reach unanimity in blaming him for all of the 2,972 deaths associated with the Sept. 11 attacks.

The verdict was a setback to the Justice Department team that doggedly pursued Moussaoui's execution even as prosecutors' theory of the case morphed several times. Moussaoui was originally suspected to be the intended 20th hijacker, and his perceived role in the plot seemed to be ever changing until his dramatic admission during the trial that he was to fly a fifth plane into the White House on Sept. 11.

Moussaoui will wind up with the sentence he would have received if the government had not pursued a death penalty after he pleaded guilty to six conspiracy counts a year ago.

Deputy Attorney General Paul McNulty, who oversaw the case before his recent promotion and was present when the verdict was read, said the trial provided "an opportunity to tell a very important story." About 50 relatives of Sept. 11 victims testified about their traumatic losses.

McNulty noted that it only takes one juror to block a death sentence and said that "accountability for the crimes committed has been achieved by the prosecution."

Defense attorney Gerald Zerkin said anyone trying to interpret the verdict form should remember that there is always inconsistency in juries' findings of mitigating factors in capital cases and that jurors might have accepted defense statements about Moussaoui as accurate while disagreeing that they were mitigating factors.

Moussaoui likely will be sent to the federal "supermax" prison in Florence, Colo., where more than 20 other Islamic terrorists are held. He will have little contact with other inmates.

Brinkema will impose Moussaoui's sentence this morning. The 37-year-old defendant will be allowed to speak during the hearing.

A death sentence would have set a precedent. No jury has imposed capital punishment on a federal defendant who did not commit murder since a 1978 Supreme Court ruling outlawed the death penalty for rapists.

Arguments recapped

Prosecutors contended that had Moussaoui told the truth about the terrorist plot after his arrest in Eagan, where he was training to fly 747 jumbo jets, the government would have at least minimized the toll on Sept. 11.

They drove home the horror of the attacks by playing videotape of jetliners turning into fireballs as they hit the Trade Center's twin towers, of people leaping 80 to 100 stories to avoid being burned to death and of the towers collapsing as victims' screams were heard over cell phones.

They showed graphic photos of body parts in New York and at the Pentagon. And for the first time publicly, they aired the cockpit voice recording of the chaos aboard United Airlines Flight 93 as a heroic passenger revolt forced the fourth hijacked plane to crash in a Pennsylvania field.

Defense lawyers argued that Moussaoui, now stymied, fabricated his role in the Sept. 11 operation in a last bid to be executed as an Al-Qaida martyr. They contended that he was just a "wannabe" lured into the terror group and had been "brainwashed" into adopting its doctrine of jihad.

Defense psychiatric experts said Moussaoui, who was in an isolated jail cell for four years until the trial started, has paranoid schizophrenia and clings to an unshakable delusion that President Bush will release him no matter what happens in court.

Star Tribune staff writer Aaron Blake contributed to this article. Greg Gordon is a correspondent in the Star Tribune Washington Bureau.