The judge presiding over the case of Zacarias Moussaoui has recessed the death penalty trial of the confessed Al Qaeda conspirator so she can determine whether the government participated in prosecutorial misconduct.

As a result, in yet another twist in the case, U.S. District Judge Leonie Brinkema is looking at whether the death penalty should be removed as an option. The trial has recessed until Wednesday.

"This is a very serious taint of a key component," Brinkema said. "We now have two very serious problems, and now this problem has no excuse. It is very difficult for the case to go forward, however, I don't want to act precipitously."

Meanwhile, the Justice Department wrote to the judge saying while it understands the behavior by one attorney in question was "reprehensible," the agency does not think it is enough to help the defense and that the emails exchanged between the attorney and some of the witnesses "may constitute attorney work product."

A lawyer who works for the Transportation Security Administration apparently has been giving transcripts to four government Federal Aviation Administration witnesses, which is in violation of government rules against coaching witnesses. "If we are going to get a fair trial ... the case should be dismissed," defense attorneys said.

The defense motion to eliminate the death penalty, if accepted, would end the trial and result in a life sentence with no chance of parole for Moussaoui. The defense did not move for a mistrial, which would have restarted the proceedings.

The judge will speak with the seven witnesses in the case herself on Tuesday. But the prosecution said it will be difficult to get one of the witnesses to the courtroom by Tuesday due to health concerns.

The development came at the opening of the fifth day of the trial. The judge's rule was that no witness should hear trial testimony in advance.

"This is the second significant error by the government affecting the constitutional rights of the defendant and the criminal justice system in this country in the context of a death case," Brinkema told lawyers in the case outside the presence of the jury.

Defense attorney Edward MacMahon moved to have the judge dismiss the death penalty as a possible outcome, saying, "this is not going to be a fair trial." In the alternative, he said, at least the judge should excuse the government's FAA witnesses from the case.

"This is not the fault of the defense," he said.

Prosecutor David Novak replied that removing the FAA witnesses would "exclude half the government's case." Novak suggested instead that the problem could be fixed by a vigorous cross-examination by the defense.

But Brinkema said she would need time to study what to do.

"In all the years I've been on the bench, I have never seen such an egregious violation of a rule on witnesses," she said.

"I'm being set up for death, my death," Moussaoui said as he left the courtroom.

Moussaoui is the only person charged in this country with the Sept. 11, 2001, attacks. He pleaded guilty in April 2005 to conspiring with Al Qaeda to hijack planes and other crimes, but he denies any role in Sept. 11. He says he was training for a possible future attack.

Click here to read the case history (pdf).

Brinkema noted that last Thursday, Novak asked a question that she ruled out of order after the defense said the question should result in a mistrial. In that question, Novak suggested that Moussaoui might have had some responsibility to go back to the FBI, after he got a lawyer, and then confess his terrorist ties.

Brinkema warned the government at that point that it was treading on shaky legal ground because she said she knew of no case where a failure to act resulted in a death penalty as a matter of law.

Even prosecutor Novak conceded that the witness coaching was "horrendously wrong."

DOJ Explains It to the Judge

The Justice Department wrote a letter to Brinkema detailing the circumstances behind the so-called "coaching," saying the witness in question did not read the material given to her by the TSA lawyer.

"Dear Judge Brinkema: We write ex parte to inform the Court of a possible violation of the sequestration order as it relates to FAA witnesses. Late in the afternoon on Friday, March 10, 2006, we learned that Carla Martin, an attorney for the Transportation Safety Administration, provided a copy of the transcript from the first day of trial to one of the witnesses from the FAA, Lynne Osmus. Ms. Osmus did not read the transcript. We then investigated Ms. Martin's contact with other current/past employees of FAA, whom Ms. Martin represented in this case (she has since been replaced)."

The letter says Justice learned over the weekend that Martin sent e-mails with the transcript from the first day's court proceedings to potential witnesses for both the government and the defense. All of the witnesses except one definitely read the e-mail but only two said they read the transcripts. Osmus is one that did not read the transcript.

"We view Ms. Martin's conduct as reprehensible and we frankly cannot fathom why she engaged in such conduct," the letter states. "As soon as we learned of her conduct, we contacted her supervisors and engaged in an investigation which yielded the above results. We also notified defense counsel of the conduct by letter, a copy of which is attached."

Criminal defense attorney Mark Eiglarsh said the whole ordeal is "damaging" to the prosecution's case.

"The image, at a minimum, that the defense will not get a fair trial will be prevalent not only in whatever decision this jury makes, but certainly on appeal," he said.

But FOX News legal contributor Lis Wiehl said there are many more options the judge can look at before dismissing the entire trial is even considered, such as instructing the jury to disregard the testimony of the witnesses in question.

"Sometimes it is just plain stupidity that one of lawyers in the chain didn't remember the rule" or broke the rule, said Wiehl, a former federal prosecutor. "I have to tell you, this is really a setback in the prosecution but I don't think the judge has to take the ultimate draconian measure" of throwing out the trial altogether, she added.

According to descriptions by the lawyers in court, it appeared that a female TSA attorney who had attended closed hearings in the case went over with four upcoming witnesses from her agency the opening statements at the trial, the government's strategy and even the transcript of the questioning of an FBI agent on the first day.

"She was at the Classified Information Act procedures hearing and she should have known it was wrong," Novak said.

MacMahon said the government had told the defense she had wanted the witnesses to be very careful in discussing the FBI agent's acknowledgment that the FBI knew long before Sept. 11, 2001 that Al Qaeda terrorists in the Philippines were working on a plan to fly an airplane into CIA headquarters.

The TSA attorney also apparently told the witnesses, erroneously Novak said, that the government was planning to say that magnetometers at airport check-ins are 100 percent effective.

Novak claimed there was no harm in that disclosure because the government is not going to make that argument.

Before the trial was recessed by Brinkema, the jury was to hear from the Minneapolis FBI agent who arrested Moussaoui — perhaps the key witness in the trial. Special Agent Harry Samit's testimony is equally important to prosecutors and the defense at Moussaoui's sentencing trial.

Samit, who has already testified for the prosecution, faced cross-examination by the defense in U.S. District Court.

Prosecutors say that Samit and the FBI would have foiled the Sept. 11 attacks had Moussaoui confessed his membership in the Al Qaeda terror network and his plans to hijack an airplane after he was arrested on Aug. 16, 2001, and interrogated by Samit.

The defense argues that Moussaoui's lies made no difference because Samit saw through them and was convinced that Moussaoui was a threat.

Up to now the burden of proof was this: To obtain the death penalty, prosecutors must first prove that Moussaoui's actions — specifically, his lies— were directly responsible for at least one death on Sept. 11.

FOX News' Sarah Herndon, Michael Levine and The Associated Press contributed to this report.