LOS ANGELES, Jun. 15 – The climactic third act of Hollywood’s strangest off-screen melodrama — the gory “ritualistic” killings of beautiful actress Sharon Tate and six others — is set to begin today.

In the grim grayness of a tiny courtroom on the top floor of the Hall of Justice, four of six defendants — all members of a roving hippie-type band go on trial charged with murder-conspiracy.

Act One — signaled by a maid’s screams from a hilltop mansion — opened Aug. 9.

Miss Tate, 26, pregnant wife of Polish film director Roman Polanski, the movies, master of the macabre, was found fatally stabbed that morning.

Also slain, in and about the house, were her former boyfriend, handsome, nationally known men’s hairdresser Jay Sebring, 35; a pretty San Francisco coffee heiress, Abigail Folger, 26; a bright, witty European playboy, Wojiciech Frykowski, 37, and a chance visitor, Steven Parent, 18, friend of the caretaker.

Detectives who swarmed through the $200,000 estate described a scene they called “ritualistic.” “PIG” was scrawled in blood on the front door; a white nylon cord looped loosely around Miss Tate’s neck was thrown over a ceiling beam and hung limply around Sebring’s neck; a hood-like cloth shrouded Sebring’s head; and an American flag was draped over a sofa.

Police said they found few clues. Then, the next night, only a few miles away, a wealthy supermarket owner, Leno LaBianca, and his wife, Rosemary, were found slain at their home in a similar manner. There were the same scrawlings in blood, as well as hoods over heads.

In act two, the spotlight shifted to a new cast of characters. It was late autumn when Police Chief Edward Davis called a press conference to declare Tate and LaBianca cases “solved.” He said it had taken 8,750 hours of work by 40 detectives.

Those arrested were identified as the hippie-type “family” of a bushy-bearded ex-convict, Charles Manson, known as “God” and “satan” to his followers. Some said the piercing-eyed Manson exercised near hypnotic power over clansmen, who did his bidding without question.

As the case developed, the prosecution accused Manson of sending five black-garbed followers on murder missions from their commune at a suburban movie ranch. They claimed the first killings were motivated by Manson’s grudge against the rich and the second were to show the killers hadn’t lost their nerve.

The accused all pleaded innocent and began a series of pre-trial courtroom courtroom maneuvers.

Act three, the trial, will feature a cast of characters that has assumed epic proportions. As the curtain rises, it reveals: seven victims, the six accused, their attorneys, two co-prosecutors, the judge, and dozens of witnesses.

At least one defendant is expected to be granted immunity and testify against the others. Four others face trial together.

If the trial begins today, Manson and three of his female followers may be strapped to chairs in the courtroom.

It was anticipated that further motions by both sides still might delay actual start of the trial proper.

Manson was dragged from the room by his long hair Friday after he flung his arms to his side and dropped his head in the pose of the crucifixion in protest that he could not act as his own attorney.

Three young women members of Manson’s hippie cult then struck similar poses and were removed from court, screaming at the judge.

All four were placed in anterooms where they could hear the pre-trial proceedings via loudspeaker.

Here is a who’s who of the cast for act three:

Charles Manson, 35. The state says of him: “The evidence conclusively shows he was the moving force behind the very inception of the conspiracy.” Manson and his followers also are charged in connection with the murder of Malibu Musician Gary Hinman.

Although the state says Manson wasn’t at the Tate mansion on Aug. 9, he is accused under a law of “vicarious liability” which holds that a conspirator is as guilty as those who did the actual killing.

Short, slender with shoulder-length brown hair and piercing eyes, Manson was born out of wedlock to a 16-year-old girl and has spent more than 20 years in reform schools or prisons, serving time on a variety of charges.

Drifting to San Francisco’s Haight-Ashbury hippie district, he attracted a following mostly of young girls and formed a communal living group. He told them he was a minstrel, minister, and wise man.

After his arrest, Manson insisted on defending himself — despite having only a fifth grade education. A judge, after watching him in action, ruled him incompetent. A veteran criminal attorney was appointed to defend him, but Manson fired the lawyer when he suggested Manson undergo psychiatric examination. Manson then hired and soon fired — a second lawyer. His attorney for the trial is Irving A. Kanarek.

• Susan Atkins, 21. Her story of the killings, told to a cellmate while she was jailed in another case, gave investigators their big break in the case. She publicly related through her attorneys what she said were details of the killings, told her story to a grand jury, then gave an account which was published in a copyright news story.

• Patricia Krenwinkel, 22. An articulate young woman with long hair and sharp features, she has been described by one judge as of “above average” intelligence.

She was arrested in Alabama and, upon extradition to California, asked to be her own lawyer. The request was denied. The public defender appointed to her went into private practice saying he wanted to devote all his time to her defense.

• Leslie Van Houten, 26. A soft spoken brunette who often wears her hair in pigtails, she has said little in courtroom appearances, but giggled nervously when she faced Manson in court.

Miss Van Houten is charged with the murders of the LaBiancas. The state says she didn’t go to the Tate home.

• Linda Kasabian, 21. Her attorney says her case has been severed from the other defendants, and the date of her trial hasn’t been set. Her lawyer and the prosecutors have indicated she probably will testify for the prosecution in return for immunity.

A pretty, sandy-haired Mother who was pregnant at the time of the slayings, she gave birth to her second child in a prison hospital ward.

• Charles (Tex) Watson, 24. Arrested near his home in McKinney, Tex., he is fighting extradition and is not expected be in California for the joint trial. His next extradition hearing in appeals court is set for Wednesday.