The trial of a $150 million libel suit filed by controversial presidential candidate Lyndon H. LaRouche Jr. against the NBC television network took a new turn yesterday when one of the jurors was excused because she feared for her personal safety.

U.S. District Court Judge James C. Cacheris in Alexandria called each of the jurors up individually during a bench conference and asked: "Do you have any fear for your personal safety?"

The questioning apparently was prompted by a note sent to the judge from the jury room, asking whether an artist who was sketching in the courtroom worked for LaRouche. LaRouche charges in the suit that two NBC broadcasts characterized him and his followers unjustly as "anti-Semitic" and "violence-prone."

The excused woman has been watching videotapes and testimony offered as evidence in the suit against the network since Monday. She walked directly to the clerk's office and requested that a federal marshal escort her home.

After yesterday's jury incident, attorneys for LaRouche could be heard arguing at the bench for a mistrial on the grounds that the question about personal safety had prejudiced the jury. But Cacheris ordered the court to proceed and Pat Lynch, the producer of one of the NBC broadcasts in question, took the witness stand for her third day of testimony.

Lynch, who was interviewed by the FBI earlier this week after reporting that she received a telephone death threat, gave testimony yesterday concerning background interviews she did for the LaRouche broadcast. Lynch testified that she interviewed former National Security Council member Dr. Norman Bailey, former Interior Secretary James Watt, Jack Cusack of the Drug Enforcement Agency and Bob Walker of the Heritage Foundation.

In videotaped segments from some of the interviews, shown in the courtroom yesterday, Walker described LaRouche as "off his rocker, actually somewhat insane," and Rep. Parren J. Mitchell (D-Md.) referred to him as a "scoundrel" whose outfit "smacks of fascism."

Others, Lynch said, spoke favorably of LaRouche and his followers. Cusack, she said, "was glowing" in response to questions about LaRouche but declined to appear on national television supporting him. In a video segment from the NBC First Camera show produced by Lynch, Bailey described LaRouche's organization as having "one of the best private intelligence services in the world."

Watt, Lynch said, had confirmed that he was "wooed for a period of time" by LaRouche, but said he had ended the relationship after deciding that "Mr. LaRouche was nuts."

LaRouche has not yet appeared at the trial proceedings.