The sale has not yet been finalised, but Zak Bagans, the star of the reality show Ghost Adventures, said he had long been looking for a home in the neighbourhood and was buying the property. “There was a very, very strong energy in the house,” said Bagans, who visits “haunted” destinations on his show and investigates paranormal activity.

“I love to investigate spirits and places,” he said. “This is a beautiful place with a very dark history.”

The “classic 1920s” home with “breathtaking, unobstructed front and back views” and “unparalleled privacy” in the Los Feliz neighbourhood was the site, 50 years ago, of one of the most notorious acts of violence in serial killer history.

On the night of August 10, 1969, Manson and a number of his cult followers sneaked into 3311 Waverly Drive, the home of Leno and Rosemary LaBianca, a middle-aged couple they had never met. Manson and Tex Watson, one of his “family” members, tied them up. By the end of the night, the LaBiancas were stabbed dozens of times, and Leno was left with a carving fork sticking out of his stomach.

The murderers scrawled “Rise” and “Death to pigs” in blood on the walls, one of them writing “Healter [sic] Skelter” on the door of the refrigerator, a reference to the Beatles song from the White Album that became the name for the white supremacist war Manson sought against black Americans.

The murder of the LaBiancas “set the city on fire”, said Bryanna Fox, associate professor of criminology at the University of South Florida. “They were literally in the wrong place, at the wrong time, which speaks to everybody. Now, everybody has to be afraid, because we can all be in the wrong place at the wrong time.”

The LaBianca case is not as well known as the gruesome killings of five people the previous night, most notably the actor Sharon Tate. Tate, who was eight and a half months pregnant, was stabbed 16 times and died while begging for the life of her child. Manson and his followers drove around the following night, looking for more victims and wound up on Waverly Drive, a street where they had gone to a party months earlier.

The LaBiancas, however, were picked at random. They owned a grocery store chain and boutique and were the “kind of people who had no enemies”, one Manson historian wrote.

The house has since been sold multiple times, with the current owners living in the property for 21 years and putting it on the market as they prepare for retirement. During that time, the Manson story has remained a pop culture obsession, with a recent resurgence of true crime podcasts and three new films, including Quentin Tarantino’s Once Upon a Time in Hollywood, out this week.

Unlike the Cielo Drive house, which was demolished in 1994, the Waverly Drive home “hasn’t been flipped and remodelled into a modern house”, Giambalvo said. “It’s mostly original.”

That fact is a draw, he said, noting details like the original pink tiles in the bathroom. The two-bedroom house has a pool and is surrounded by “lush greenery” on a 31,000 sq ft lot, making it “so private and quiet, you can’t believe it”.

He advertised it as “truly one of a kind”, not because of the murders, but rather because the property has stunning views of downtown Los Angeles in the front and the San Gabriel Mountains in the rear.

“It’s so peaceful and serene and magical with the dual views. I’m wondering if that’s the reason people haven’t asked about [the murders], because it’s so amazing,” he added.

It can be a strange and challenging process to sell an infamous murder mansion.

“In my experience, iffy people buy those kinds of houses,” said Stephen Shapiro, chairman of Westside Estate Agency, a Los Angeles company that twice sold the Cielo Drive property where Tate was killed.

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A real estate investor who bought that house in 1988 went to jail the next year for a financial fraud case. Shapiro said he also sold another famous murder house to someone who later went to jail.

At Cielo Drive, Shapiro’s agents would always disclose the bloody history, and “most people immediately backed off”. Those who did show up “had a different kind of sensibility” or toured the property out of morbid curiosity and never planned to buy it.

Shapiro wasn’t directly involved in the sale and only visited once – and found himself unable to go inside.

“I’m not the type of person that relies on astrology … or believes in the occult or afterlife,” he said, “but I couldn’t go in the house. I got out of the car and I felt it in the motor court. I could feel evil.”

Giambalvo has not had a similar experience. On the contrary, he joked with the sellers that every time he visited, they had to leave him alone for five minutes, so he could stand in silence and enjoy the view. The company also disclosed the history to potential buyers, and if anyone were to ask him specifics about it, his plan was to say “research LaBianca house” and leave it at that.

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He said he had priced it just below market value, but that appraisers struggled to tell him whether the history would be a detractor since “there is not a bank of information on famous murder homes in LA”.

Bagans, whose purchase of the property is now in escrow, declined to say what his plans were for the property or if he intended to do any formal paranormal investigations once he took over.

But, he added, “If I’m spending time there and come into contact with anything, that’s the world I live in”.

Criminology professor Fox said she was surprised the home hadn’t been demolished: “I could not imagine hanging a TV on the wall where [words] were written in someone else’s blood.”

But, she added, “with real estate, you only have to have one buyer”.