The death-penalty trial of Al Qaeda conspirator Zacarias Moussaoui is back on track after a judge reversed course and agreed to admit some evidence about aviation security.

U.S. District Judge Leonie M. Brinkema relented Friday from her earlier order barring all such testimony. She had issued that ruling Tuesday as punishment for the alleged misconduct of Transportation Security Administration lawyer Carla J. Martin, who coached witnesses.

"It would be unfortunate if this case could not go forward to some final resolution," Brinkema told trial attorneys in a telephone conference. Moussaoui, a French citizen, is the only person charged in this country in connection with the Al Qaeda terror network'sSept. 11, 2001, attacks on the World Trade Center and the Pentagon.

The trial, begun March 6 and suspended for a week to deal with the misconduct, is to resume Monday with the jury back in court.

Late Friday, Moussaoui's lawyers asked Brinkema to further investigate Martin before allowing any aviation testimony. Prosecutors agreed, if Martin is willing to testify. Brinkema gave no immediate response.

The judge accepted a compromise proposal by the government. It allows prosecutors to present limited testimony about what the government could have done to enhance aviation security before the Sept. 11 attacks if Moussaoui had not lied to FBI agents Aug. 16-17, 2001, about his Al Qaeda membership and plans to crash a jetliner into the White House.

Prosecutors had told Brinkema their case would be gutted without at least some testimony on aviation security. While they disputed her ruling that the aviation security evidence was contaminated beyond repair by Martin, prosecutors suggested using a new, substitute witness and documents that Martin had no contact with.

Prosecutors said a substitute witness could be found who worked at the Federal Aviation Administration around Sept. 11 and could discuss how government used "no-fly" lists to bar specific terrorist suspects from airplanes.

The testimony is crucial because prosecutors must prove that Moussaoui's actions led directly to at least one death on Sept. 11 to obtain the death penalty. They argue that Moussaoui's lies about his true intentions prevented the FBI from identifying some hijackers in advance and prevented the FAA from taking airport security steps to keep them off airplanes.

Moussaoui's lawyers had urged Brinkema not to reconsider. They said federal law since 1790 has required that the defense be notified of the government's witnesses at least three days before trial in death-penalty cases. Allowing new witnesses mid-trial would leave them unprepared, the defense argued.

Brinkema acknowledged that substitute government witnesses would present problems for the defense, including finding rebuttal witnesses.

Moussaoui pleaded guilty in April to conspiring with Al Qaeda to crash airplanes into U.S. buildings. But Moussaoui denies any role in 9/11 and says he was training for a possible later attack on the White House. The current trial is to determine whether he is executed or spends life in prison.

A hearing Tuesday revealed that Martin sent current and former FAA employees a transcript of the trial's first day and coached them on how to testify about certain topics to deflect the kinds of attacks the defense mounted that day.