"You want to link me to certain facts that will guarantee my death," Mossaoui told U.S. District Judge Leonie Brinkema as he withdrew a plea he tried to make an hour earlier.
"Because of my obligation to my creator, Allah, and to save and defend my life I withdraw my guilty plea," he told a packed courtroom in still another stunning change of events.
The judge accepted his decision and said the government cannot use his earlier plea against him.
Moussaoui had begun his arraignment Thursday by saying he wanted to plead guilty to the first four of six charges in the indictment the government brought against him last December. All four of the charges carry the death penalty.
But the hearing took a turn when Brinkema declared she did not believe Moussaoui intended to admit his full guilt as laid out in the indictment.
"At this point I do not believe you are prepared to make a guilty plea because you are not prepared to admit the essence of the conspiracy," Brinkema said after Moussaoui tried to plead guilty to the first charge in his indictment.
The exchange had placed in doubt Moussaoui's efforts to plead to some of the charges against him.
Moussaoui, a Frenchman and the lone person charged with conspiring with the September hijackers, balked when the judge asked him directly if he had joined with members of al Qaeda in a plan to seize aircraft.
"I want a recess," he asked. The judge agreed.
The judge's decision ended a topsy-turvy arraignment that began with Moussaoui saying he intended to plead guilty.
"Today, I truthfully will enter on some of the charges, not all, a plea of guilty," Moussaoui declared.
"It should not be misunderstood that I endorse the entire indictment. There is enough factual basis for me to plead guilty in a truthful manner," the French citizen said.
Moussaoui told the court he intended to plead guilty to the first four charges in the indictment, accusing him of conspiracy to commit acts of terrorism, aircraft piracy, aircraft destruction and using weapons of mass destruction. All four charges carry the maximum penalty of death.
But the only man charged in the September attacks said he was not pleading to the last two charges. Those two charges accuse him of attempting to murder government employees and attempting to destroy property.
When the judge began to ask him about his role in the Sept. 11 conspiracy, Moussaoui gave his own explanation as his mother from France watched on in the audience.
"They allege I provided a guest house, I accept," he said. "If they allege provide training, it is possible for me to accept," he said. "I plead guilty to what is in the indictment, but it still doesn't put me on the plane."
"I want to plead only for what I did, not for what they say I did," Moussaoui declared at one point in the proceedings.
The judge never accepted any of the guilty pleas.
During the middle of the hearing, the court was informed that a federal appeals court had rejected a request from a private lawyer who tried to represent Moussaoui. The lawyer wanted to stop the hearing.
Before Moussaoui made his statements, Brinkema also rejected a request by Moussaoui's court-appointed attorneys to delay Thursday's arraignment and to order a full-scale mental evaluation. The lawyers, whom Moussaoui fired, have been arguing that they believe he is mentally ill and unable to represent himself.
They cited as evidence more than a hundred handwritten court briefs that Moussaoui has made — some making wild allegations.
"His pleadings are somewhat confrontational and somewhat unusual ... but they do not give the court any basis to assume that the defendant is not competent," the judge ruled.
Brinkema noted that the mother had written the court urging that her son's guilty pleas not be permitted.
Brinkema had sent a letter to Moussaoui noting that she had asked the government to outline the facts of the case against him. She asked him if he had seen the letter and agreed with the government's facts.
Moussaoui said the government had not allowed him to tell what he knows to a grand jury but said he wanted to use Thursday's court session to divulge what he knew about Sept. 11.
Moussaoui said the crux of the case against him is "whether I came to the U.S. to commit acts of terrorism. ... That's what I want to talk to U.S. people, Americans, who are my enemies."
U.S. Attorney Paul McNulty had argued that Moussaoui was competent to make his own plea and that his defense lawyers request was "an attempt to add an artificial barrier to the defendant's clear intent to plead guilty."
CBS News.com Legal Analyst Andrew Cohen says the judge's initial decision on Moussaoui's competence wasn't too surprising.
"The judge has pretty consistently believed Moussaoui to be legally competent to represent himself even though he has fairly frequently frustrated her with his in-court antics and his bizarre motions. So she is simply sticking to the same rulings she made for the past several weeks," Cohen says.
Already heavy security at the U.S. Courthouse not far from the Pentagon, site of one of the Sept. 11 attacks, was tightened further for Moussaoui's appearance.
The defendant was driven to the courthouse roughly two hours before his scheduled appearance.
The security perimeter of hydraulic barriers was widened for Moussaoui's return to the courtroom where he attempted a week earlier to plead guilty.
Moussaoui last week admitted he was a member of Osama bin Laden's al-Qaida network but in the past had denied aiding the hijackers. Brinkema told him he could not plead guilty by denying his personal role.
A week ago, Brinkema refused to accept Moussaoui's guilty plea, giving him more time to think about it. Last week Moussaoui, 34, pleaded guilty and stunned the court by saying he was a member of al Qaeda, had knowledge of the Sept. 11 attacks and had pledged his allegiance to Osama bin Laden.
The United States blames bin Laden and al Qaeda for the hijacked plane attacks that killed 3,000 people. U.S. officials believe Moussaoui, a French citizen of Moroccan descent who was detained on immigration charges on Sept. 11, was meant to be the 20th hijacker.
Late Thursday, Moussaoui's mother issued as statement saying her son was "too emotional" to represent himself in court.
"His recent behavior perfectly illustrates that he is too emotional to represent himself," said the mother, Aicha el-Wafi. "In June, I visited him four times. I did not recognize the child I have given birth to; he has changed for the worse physically and psychologically."
She said solitary confinement has taken a toll on her son, who has been in custody since authorities in Minnesota arrested him Aug. 16.
"It was also clear from today that Zacarias did not understand the implications of what he said last week or even what he was admitting to," she said.