The government can continue to seek the death penalty against confessed Al Qaeda conspirator Zacarias Moussaoui, the judge of the case said Tuesday.

Frustrated by a number of government missteps, Judge Leonie Brinkema oversaw a daylong hearing into whether coming witnesses had been tainted by improper coaching by a federal lawyer before ruling.

"I don't think in the annals of criminal law there has ever been a case with this many significant problems," Brinkema said. "More problems arose today that none of us knew about yesterday."

Brinkema's also ruled testimony about aviation security measures would not be allowed during the rest of the trial. Prosecutors had said previously that testimony from aviation officials would comprise half their case.

Originally, the government's case had two parts. Prosecutors intended to show active steps the FBI could have taken and defensive measures aviation officials could have taken to thwart the Sept. 11, 2001, attacks if Moussaoui had not lied about his terrorist connections when he was arrested a month earlier.

But problems arose. Brinkema said that her order to isolate planned witnesses from trial transcripts and news reports had been violated.

She also said she was troubled that one witness sought by defense lawyers was told by federal attorney Carla J. Martin that he could not speak to them and that Martin falsely told the defense that two others were not willing to speak to them.

"I wouldn't trust anything Martin had anything to do with at this point," Brinkema said. The jury was not present for Tuesday's questioning and ruling.

Brinkema said the proper remedy was not to eliminate the government's bid for the death penalty — as the defense asked — but to acknowledge that parts of the case dealing with aviation security matters were now "irremediably contaminated."

Prosecutor Rob Spencer immediately told the judge the government objected to excluding all such testimony and exhibits and would consider appealing her ruling.

Earlier Tuesday, four federal aviation officials scheduled to testify in the sentencing trial said that coaching would not affect what they would tell the jury. But they disclosed new problems in the government's handling of witnesses.

Among those problems:

— Government lawyers sent a letter Feb. 14 saying that at least three federal aviation officials sought as defense witnesses refused to talk to defense lawyers. The three said they had never seen the letter and one of them said he would have been willing to talk to the defense.

— Martin told one official, sought as a defense witness, that he was not to have contact with defense attorneys.

— Two of the witnesses read and watched news coverage of the week-old trial despite the judge's order they not follow the case. The government admitted it did not advise witnesses of the judge's order governing their conduct.

— Martin not only e-mailed seven witnesses about trial events but also told one person that the defense was trying to portray Moussaoui as "cuckoo."

As Robert White, a Transportation Security Administration intelligence liaison officer, was testifying that he had not seen the letter saying he was unwilling to talk to talk defense lawyers, Judge Brinkema interrupted the questioning.

"Did you see the subpoena issued for you?" she asked.

"No," White replied.

TSA intelligence analyst John Hawley and Matthew Kormann, an officer in the TSA intelligence service, also said they were unaware that a letter had been sent saying they refused to talk to the defense.

Martin, the Transportation Security Administration attorney who prompted Tuesday's hearing without the jury present, also was summoned. But her questioning was delayed when she told the judge she had not been able to arrange for her own lawyer. Brinkema had warned her that "you violated a court order and could be held in civil or criminal contempt," and directed her to return with a lawyer by Wednesday morning.

Martin had been the government attorney for the seven witnesses and worked with prosecutors on preparing evidence.

Kormann also testified that in addition to receiving an e-mail from Martin, she told him at a meeting last week about the defense's cross-examination of an FBI agent.

Claudio Manno, deputy chief of security for the Federal Aviation Administration on Sept. 11, 2001, and Pat McDonnell, who retired in May 2001 as FAA director of intelligence, both testified they had been reading and watching news accounts of the trial and were not told until last Friday that Brinkema had ordered witnesses not to follow the proceedings.

Kormann, McDonald, Manno and Manno's boss, Lynne Osmus, all denied in court that they would alter their testimony in any way as a result of being coached last week by Martin.

Defense lawyer Edward MacMahon also elicited testimony Tuesday that prosecutor David Novak had conducted a joint telephone conversation with two upcoming witnesses, despite long-standing prohibitions against trial witnesses interacting before they testify.

Novak told Brinkema the phone call, which apparently happened after the judge issued rules on witnesses on Feb. 22, concerned only the logistics of trial exhibits, not the substance of testimony.

MacMahon had moved to bar the government from pursuing the death penalty.

Moussaoui pleaded guilty in April to conspiring with Al Qaeda to fly airplanes into U.S. buildings; this trial is to determine whether he will be executed or spend life behind bars.

The only person charged in this country in Al Qaeda's Sept. 11, 2001, attacks, Moussaoui has denied having any role in those attacks. He says he was training for a possible future attack.

The trial will resume Monday to give the government a chance to appeal the decision to bar testimony.

The Associated Press contributed to this report.