Zacarias Moussaoui, the only person indicted as a Sept. 11 conspirator, knows enough about Western culture to mention Watergate's Deep Throat, the movie Gladiator and American slang like "dis" for disrespect.

Through dozens of bizarre handwritten motions and his own courtroom antics, Moussaoui has painted a portrait of himself as intelligent, yet possibly paranoid. His behavior has left court-appointed experts struggling to understand him and has prompted the trial judge to re-evaluate his mental competency.

"He has one foot in the real world and one foot in the delusional world," said Dr. Xavier Amador, a clinical psychologist at Columbia University Medical School and an adviser to Moussaoui's court-appointed defense lawyers. "As a result, we see instances where he's clearly connected to reality alongside instances of psychotic delusion," he said in an interview.

Moussaoui has alleged the judge and his court-appointed lawyers are plotting to kill him and that the FBI "cynically allow Sept. 11 in order to destroy Afghanistan."

U.S. District Judge Leonie Brinkema could change her mind on Moussaoui's competence before his Sept. 30 trial date. He is to be arraigned Thursday on a third indictment that includes allegations that could lead to the death penalty.

"Do you think that I am crazy to see your Doctor Frankeinstein," Moussaoui wrote July 11, refusing to meet again with a court-appointed psychiatrist who previously found him competent.

To resolve the competency question, Brinkema must consider Moussaoui's fervent religious beliefs and his desire to use the courtroom as a public forum.

"You need to differentiate his religious and political beliefs from beliefs that may be attributable to mental illness and, in this case, the interweaving of the two," said Richard Bonnie, a professor at the University of Virginia School of Law and director of the university's Institute of Law, Psychiatry and Public Policy.

Bonnie, who is advising Moussaoui's court-appointed lawyers, added in an interview, "Being stubborn and hardheaded does not necessarily mean being mentally ill. It's a challenge for clinicians to differentiate between personal characteristics that might be self-defeating and symptoms of severe mental illness."

The judge has ordered more evaluation by mental health experts. Their subject, 34, has been a study in contrasts.

Moussaoui has been rational enough to seek records of a money transfer crucial to his indictment, even as he demanded the government apologize "for the Insult to the Coran" and that the judge order an independent examination of "a Square Fan (70cm x 70cm) 'Mystereously' Left on My Car."

Arrested last August on immigration violations when flight school employees in Minnesota became suspicious of his conduct, Moussaoui recently wrote: "So far so good, keep going Brinkema but don't forget it's the landing that is difficult."

Moussaoui has researched the law enough to quote from previous court rulings, yet he has demonstrated a lack of basic legal knowledge.

He tried to plead "no contest" to a revised indictment, apparently unaware that was equivalent to pleading guilty. The judge explained that to him and entered an innocent plea on his behalf.

"A critical issue there is whether he lacks a rational understanding of proceedings against him," said Bonnie, adding the answer could determine not just whether Moussaoui continues to represent himself but whether he's competent to stand trial.

Amador likened Moussaoui's pleadings to making a movie, with one significant difference.

"A movie has logic from one snapshot to the next," he said, but Moussaoui only appears logical in individual frames.

"When you look at all the frames together, it's practically incoherent," Amador said. "He believes the judge is conspiring with President Bush to murder him, but he would like the judge to preside in his trial without a jury."

When the judge allowed Moussaoui, a man of Moroccan descent, to represent himself, she attributed some of his legal difficulties to his different cultural upbringing.

Frank Dunham Jr., the court-appointed defense attorney Moussaoui has sought to fire, said the defendant has a good understanding of Western culture.

"America you are bankrupt," Moussaoui wrote recently in one court motion. "Long have passed the time of deep throat," he said in a reference to The Washington Post's secret Watergate source. "Now it is deep bribe with the fight against terrorism at the end of the financial year."

Dunham said the reference shows Moussaoui is aware of Watergate and the corporate scandals that have rocked Wall Street. He knew enough to use the word "dis" regarding a judge's order, Dunham added in an interview.

Moussaoui also likened Bush to the Roman emperor in the movie Gladiator.

"The one who say that he was going to return honors to the office was definitely talking about Ceasar Type Honors like in Gladiator. Stabbing the enemy in the back before the fight. Not surprising for Daddy son. Leading [or I must say cheating] from the back," he wrote.