LOS ANGELES, Jul. 27 – The state’s only alleged eyewitness to the Sharon Tate murders was scheduled to testify under courtroom guard today against Charles Manson and three female members of his “family.”

Linda Kasabian, 20, who will be granted immunity in return for telling her story, was to take the stand after the defense cross-examine a young caretaker at the Tate estate the night of the slayings last Aug. 8.9.

William Garretson, 19, told the jury in the trial’s opening testimony that he was awakened at dawn but heard no shots, screams, or loud noises in his bungalow which it located on the other side of the swimming pool from the main residence.

Garretson said he first learned of the killings of Miss Tate and four others when police burst into his cottage with drawn guns the next morning. He was at first charged with suspicion of murder in the slayings but later released.

Mrs. Kasabian, who lived with the hippie cult at the Spahn Ranch commune at the time of the five killings at the Tate home and two others at the home of grocer Leno LaBianca has been isolated from the other defendants and kept under special guard pending her testimony.

Deputy District Attorney Vincent T. Bugliosi said in his opening statement that Mrs. Kasabian actually saw three killings at the estate rented by Roman Polanski, the movie director husband of the blonde actress.

Bugliosi said she witnessed the killings of coffee heiress Abigail Folger, Polish writer Voitych Frykowski and 18-year-old Steven Parent, who had been visiting young Garretson. Their bodies were found outside the home. Miss Tate and hair stylist Jay Sebring were inside the rambling ranch home.

Mrs. Kasabian was said by the state to have driven members of the “family” the next night to the LaBianca home and acted as a lookout there. Bugliosi said Manson ordered her and others of his cult to carry out a killing at a third home that same night of Aug. 9 in the beach front community of Venice, Calif. But, he said, Mrs. Kasabian deliberately thwarted it by knocking on the wrong apartment door.

On trial with Manson are Susan Atkins, Patricia Krenwinkel and Leslie Van Houten.

The district attorney charged that Manson ordered the murders in an attempt to touch off a black-white race war by having the killings blamed on Negroes.

By JACK V. FOX