LOS ANGELES, Feb. 25 – Despite threats against her life, Shelley Joyce Nadell says she intends to testify as a key witness in the murder trial of Charles Manson and his followers.

Mrs. Nadell, 31, talked in a copyrighted television interview about her role as an informant in the Sharon Tate murder case. The interview was broadcast over television station KNXT.

Only her nervous hands betrayed a calm manner as she spoke in what the interviewer called a hideout in an eastern city.

Authorities say Mrs. Nadell’s information led to the indictment of Manson and five others on charges of killing Miss Tate and four others last Aug. 9, then killing a market owner and his wife the next night.

Mrs. Nadell shared a jail cell with Susan Atkins, one of the Tate case defendants. Asked if she would return to Los Angeles to testify, Mrs. Nadell replied: “Definitely. I told the police I never would have started all this unless I intended to follow it through.”

Mrs. Nadell was released from jail two weeks ago after she was acquitted of forging narcotics prescriptions.

“I was threatened in jail numerous times,” she told the interviewer. “I was told I would be dead in two weeks.”

She said she felt she had to testify because “these people really are sick. If they’re turned free, there’ll be many other killings.”