An FBI agent testified Monday his superiors repeatedly ignored his warnings before 9/11 that Zacarias Moussaoui might be a terrorist intent on hijacking an airliner.

Agent Harry Samit, questioned by defense attorney Edward MacMahon in Moussaoui's death penalty trial, said he referred to Moussaoui in the context of terrorism some 70 times in communications with superiors after arresting him Aug. 16, 2001, but failed to get the FBI to conduct an all-out investigation.

Moussaoui is the only person charged in this country in connection with the 9/11 terror attacks on the United States.

MacMahon walked Samit through a lengthy report that he filed to his bosses and other FBI investigative units on Aug. 18, 2001. The memo listed all the reasons Samit was suspicious of Moussaoui as a terrorist who might be trying to hijack airplanes.

Every time MacMahon read an example of Samit's suspicions, the agent acknowledged that FBI headquarters never called him back to discuss his concerns.

"You needed people in Washington to help you out," MacMahon suggested at one point.

"Yes," Samit said.

"They didn't do that, did they?"

Samit said no.

He confirmed under questioning that he had attributed FBI inaction to "obstructionism, criminal negligence and careerism" in an earlier report.

Moussaoui pleaded guilty in April to conspiring with Al Qaeda to hijack aircraft and commit other crimes. The sentencing trial will determine his punishment: death or life in prison.

To obtain the death penalty, prosecutors must prove that Moussaoui caused at least one death on Sept. 11. They argue he did just that by lying to agents after his arrest and refusing to reveal his Al Qaeda membership and his terrorist ties.

Moussaoui denies he had anything to do with 9/11 and says he was training for a future attack.

MacMahon questioned Samit on whether the government could have legally searched Moussaoui's Minnesota hotel room without first obtaining a warrant.

Samit said that in certain circumstances agents can conduct a search on foreign nationals immediately and obtain a warrant after the fact. But he said in Moussaoui's case, he and his supervisors determined that it would be best to arrest Moussaoui first.

Samit testified before the trial's recess last week that Moussaoui lied to him after his arrest and thwarted his ability to obtain a search warrant. Samit said that the FBI would have launched an all-out investigation if it had been able to search Moussaoui's belongings.

"You blew an opportunity to search ... without arresting him?" MacMahon asked Samit.

Samit responded, "That's totally false."

He said he found himself in a bureaucratic bind because he had opened an intelligence investigation on Moussaoui rather than a criminal investigation and therefore needed Justice Department approval to get a search warrant. Many of the barriers between criminal and intelligence investigations were removed after 9/11.

Resumption of the trial followed a one-week delay while U.S. District Judge Leonie Brinkema mulled whether to allow testimony by aviation witnesses considered vital to the government's effort to secure the death penalty for Moussaoui.

The delay followed revelations that a lawyer with the Transportation Security Administration, Carla Martin, had improperly coached witnesses on their testimony.

Brinkema uncovered even more misconduct during a hearing: Martin falsely told defense attorneys that two TSA employees sought by the defense as potential witnesses were unwilling to meet with the defense, witnesses testified.

Brinkema considered tossing out the government's death-penalty case entirely, but instead ruled that the government could not present any testimony about aviation security in their case to the jury.

Prosecutors responded that Brinkema's order amounted to pulling the plug on the entire case and asked her to reconsider. They said the excluded testimony was crucial because they needed to show the jury what security measures could have been implemented at the nation's airports if aviation officials had known of the threat posed by Moussaoui and his Al Qaeda co-conspirators.

Brinkema relented on Friday and revised her ruling, allowing prosecutors to present testimony from aviation witnesses who were unexposed to Martin's taint.

Defense attorneys asked Brinkema late Friday to question Martin about her actions before allowing any aviation testimony, but they got no immediate ruling.