Los Angeles  - It was a murder spree that shocked the world, and 40 years later America is still drawn to the shocking story.

The Manson family murders of August 9, 1969, held a morbid fascination for many reasons - the manic charisma of the group's leader, Charles Manson, the Hollywood profiles of some of the victims, the sheer brutality of the crimes and the way that Manson turned innocent, all-American young men and women into unblinking, cold-blooded killers.

Author Joan Didion pointed out that the Manson case came after a historic wave of change.

"The '60s ended abruptly on August 9, 1969," Didion wrote in her memoir of the time, "ended at the exact moment when word of the murders traveled like brushfire through the community. The tension broke that day. The paranoia was fulfilled."

The horror had its roots in the troubled childhood of Manson.

Born to a 16-year-old mother in Ohio, he was repeatedly rejected, shunted in and out of foster homes, juvenile detention centers and prisons. He survived on a life of petty crime. When he was released from a five-year stint in jail in 1966 at age 32, he had spent more than half his life in prisons and other institutions.

The next year, Manson moved to San Francisco, and using his charm and charisma with women, and some of the Scientology teaching he had picked up in jail, he established himself as a guru in the epicenter of hippiedom during the Summer of Love, before moving the Manson family to southern California.

Manson promoted himself to the Hollywood community as an artist and philosopher. But to his inner group, he preached a dogma of race war, which would see his self-proclaimed "family" emerge as the rulers of a society rent asunder after blacks had risen up against their oppression.

He called these race wars Helter Skelter, after the song on The Beatles' White Album, which he believed predicted the coming apocalypse.

On August 8, Manson ordered his right-hand man, Charles "Tex" Watson, to take three women, Susan Atkins, Linda Kasabian and Patricia Krenwinkel, to the house that had been rented out to director Roman Polanski and his eight-months pregnant wife, actress Sharon Tate.

With one order - "Now is the time for Helter Skelter" - he told them to "totally destroy" everyone in the house "as gruesome as you can."

They were true to his commands, brutally killing the five occupants in the house and using their blood to daub slogans on the walls. Polanski was in London at the time, but Tate was stabbed 16 times until she and her unborn baby died.

The killing spree continued the next day, when the four murderers were joined by Manson himself and two others of the Manson clan, Leslie Van Houten and Steve Grogan, in the grizzly murders of supermarket executive Leno LaBianca and his wife, Rosemary.

Manson was arrested on August 16 on suspicion of auto theft. Only several months later did authorities piece together the involvement of the leader and his followers in the horrific crimes.

The trial only spread the notoriety of the defendants.

Manson carved an X and later a swastika on his forehead - and the co-defendants soon copied his lead. He tried to physically attack the judge, his followers drugged prosecution witnesses, and one of the defence attorneys died in mysterious circumstances.

The defendants were found guilty and condemned, but their death sentences were automatically reduced to life in prison when the California Supreme Court abolished the death penalty in 1972.

Manson, now 74, has retained his notoriety over the years as America sought to understand how his group could descend into such gratuitous violence.

"These were people whose self-hatred was so strong that they had no way of dealing with it," says sociology professor Howard Kaplan.

"They associated with other outcasts and formed their own identity. Once they were captured, they seemed to enjoy the media attention, especially Manson, who disrupted the trial many times. From their acts of violence, they found out that they would get attention, and in doing so, they 'mattered' in some strange way."

Prosecutor Vincent Bugliosi said the apparent random nature of the crime struck fear throughout Los Angeles and the movie world and fueled a spike in the sale of guns and guard dogs.

"The killings tapped a feeling of dread," he told Newsweek magazine. "There was a feeling (the killers) could be our own children."

Manson has never expressed remorse for the killings, but the now ageing people who blindly followed him have apologized.

"I'm appalled (at what I did)," a terminally ill Atkins said just prior to an unsuccessful parole attempt last year.

Krenwinkle voiced similar regret: "I feel terrible about it, but I cannot change it." (dpa)