In 1975, a 4,000-square-foot house with a finished basement in a peaceful New York suburb, on a quarter-acre lot boasting a heated pool and its own boat dock, went on the market for $100,000. 

A listing that should have begged only one question: What's the catch?

Well, George and Kathy Lutz knew—23-year-old Ronald DeFeo Jr. had killed his parents and four siblings in the house barely a year beforehand—but the couple wanted a nice place to start their life together, so they offered $80,000 and bought the lot, including some old pieces of furniture dappled with visible traces of blood.

The 28 days the Lutz family—George, Kathy and her kids Danny, Christopher and Melissa from a previous marriage—spent at 112 Ocean Ave. is the stuff of, quite literally, legend. What happened—or, one must ask, did not happen—in the house has fueled its own true crime-meets-psychic-phenomena industry that all started with Jay Anson's 1977 book The Amityville Horror and the 1979 movie of the same name starring James Brolin and Margot Kidder.

Almost 50 years later, warring mysteries endure, and the new MGM+ docuseries Amityville: An Origin Story sets out to unpack the different types of horror at play here, through the eyes of paranormal investigators, priests, detectives, lawyers, friends of the DeFeo and Lutz families and one of the kids who lived through it, many of them going on camera for the first time.

Series director Jack Riccobono told E! News that the aim was to "take apart what makes it tick and understand what was it in the '70s that made this story explode and capture people's imaginations in a way that it's still doing to this day."

And while he acknowledged that the topic is well-plumbed, he feels that the culture that helped enshrine the happenings in Amityville in the annals of horror history is still perfectly recognizable.

"We're living in a moment right now," Riccobono explained, "of mass anxiety, of people who were just in lockdown from COVID, trapped in their homes with their families and trying to figure things out. And people are really obsessed with the occult right now, and the paranormal and conspiracy theories. So much of that was present in the '70s and played such a big part in the Amityville Horror becoming what it became."

Here are the bones of that origin story ahead of the show's April 23 premiere:

What happened to the DeFeo family?

On Nov. 13, 1974, Ronald Jr. returned to his family's Amityville home sometime after 6:30 p.m. and found his parents, Ronald Sr., 43, and Louise DeFeo, 42, sisters Dawn, 18, and Allison, 13, and brothers Mark, 12, and John Matthew, 7, dead. 

At least, that's what Ronald first told authorities, according to police at the time. 

"It could be anything," Amityville Village Police Sgt. William Smith told reporters. "We're not ruling out robbery."

Ronald was initially taken to the police station for his own protection, considering his entire family had just been wiped out and—as friends of the DeFeos remember in Amityville: Origin Story—Ronald Sr. was rumored to have mob ties.

The next day, however, Ronald was arrested on suspicion of murder.

Investigators determined that the DeFeos—who were found in their beds, dressed in night clothes, all shot to death—had been killed sometime during the early morning hours of Nov. 13. Ronald, who worked at the family-owned car dealership his father managed in Brooklyn, said he had come home late the night of the 12th and gone straight to bed, then left the next morning without noticing anything amiss, according to Suffolk Chief of Detectives Patrick Mellon.

Police said that witnesses put Ronald at a nearby bar three times starting at 5 p.m. on the 13th, his last appearance coming after he supposedly found the bodies at 6:38 p.m., when he ran into the bar shouting, "My father and mother have been shot!"

One of the patrons told police he and several other men got into Ronald's car and went back with him to the house. After seeing the four dead kids in their beds, one of the men called 9-1-1. Police were there by 7 p.m.

What did Ronald DeFeo Jr. say about the murders of his family?

Investigators told the New York Times a few days after Ronald Jr. was arrested that the suspect claimed he'd slipped barbiturates into his family's food the night of the murders. He also shared that he'd dumped the murder weapon in the water behind the house, and divers found a .35 caliber Marlin rifle in Amityville Creek.

Dr. Howard C. Edelman, deputy chief medical examiner for Suffolk County, said all of the bodies had been found face down (the parents were each shot twice in the back, the girls once each in the head, the boys once each in the back), all with their hands raised above their heads—a situation the pathologist called "bizarre." 

Ronald ended up pleading not guilty by reason of insanity at trial, during which he testified about going from room to room and pulling the trigger, killing his family. 

Prosecutors argued that Ronald was looking for cash his father had in a lockbox, while the defense maintained an insane hatred of his family led him to kill. Defense witness Dr. Daniel Schwartz testified that Ronald "did not know it was wrong" to murder his family, but rather, "because of his mental illness, he was convinced that it was correct." 

Regardless, after seven weeks (making it the longest-ever trial held in Suffolk County at the time), Ronald was convicted of six counts of murder on Nov. 21, 1975, and sentenced to 25 years to life in prison.

Needless to say, what he had done couldn't be easily attributed to one theory or another, and the real-life horror lingered in Amityville—for many reasons.

Who were George and Kathy Lutz?

George was a former Marine who said he served in Vietnam (it's only been verified that he served during Vietnam) and later joined a motorcycle club and got into transcendental meditation. His first marriage had been annulled when he met Kathy, who was divorced from the father of her three kids.

In Amityville: Origin Story, Kathy's son Chris Quaratino (who says he changed his name back from Lutz after his mother died in 2004 to disconnect from the Amityville hysteria) called George "a man figure that was there and kind to us, and mom liked him. That was that."

They moved into 112 Ocean Ave. a week before Christmas in 1975. Danny, Chris and Melissa were respectively 9, 7 and 5.

"We felt we were home," George said later during a talk show appearance included in the reels of retro footage utilized in the series. Kathy noted, "I described the house as charming the first time I saw it, 'cause that's what I thought of it."

Even George—who most perpetuated the myth of what his family experienced in that house, to the consternation of many—admitted that The Amityville Horror film with its bleeding walls took creative liberties.

But by all accounts, enough happened during the four weeks the Lutzes lived there to freak them (as well as a number of their friends, and their local priest) out and send them fleeing, never to return.

Chris expresses his outrage throughout the MGM+ series over the exploitative arc the telling of his family's story took over the years, starting with Anson's book.

And he in no small part blames his former stepfather for embellishing what was already a gripping true story. He also scoffs at all the characters who became entangled in the lore, including Ed and Lorraine Warren—the real-life paranormal investigators played by Patrick Wilson and Vera Farmiga in The Conjuring franchise, whose 1976 investigation of the DeFeo house factors into the second film. 

Lorraine said at the time "it's the closest to hell she ever wanted to get," director Riccobono told E!, "and that leads to the book, which leads to the movie, so you have this runaway train."

Incidentally, Chris maintains that the Lutz family horrors are not a hoax and he believes George at least partly caused what happened to them by tempting forces he didn't understand. (In later interviews, George claimed to have no knowledge of the occult, and Amityville: An Origin Story features a number of people who say otherwise.)

"What really happened is, to me, more traumatic," Chris says in the series' first episode, "and it was something that I would have liked to have just forgotten about."

George died of heart disease in 2006 when he was 59, but not before suing Chris for trademark infringement after his former stepson (he and Kathy divorced in 1988) bought the rights to AmityvilleHorror.com upon finding out George had sanctioned yet another movie related to their ordeal.

"At the core," Riccobono said, "it's really a story about these two families and some of the things that happened behind closed doors and the secrets that families keep. There's a real human component to it." 

And he didn't set out to debunk the supernatural elements of the story or make a case for them. "Hearing what people believe, what they believe happened to them" was what excited him about the project, he said. "We all live in this crazy world and have our own perceptions of what's going on and reflect that back to each other in different ways. A lot of what this series is about is the nature of truth."

Why was the Amityville house supposedly haunted?

The basic supernatural lore surrounding The Amityville Horror would have it that George Lutz was a perfectly nice, normal guy (and in Ryan Reynolds' case in the 2005 remake, a perfectly nice guy with an eight-pack) who was increasingly haunted by the evil that Ronald had perpetuated in the house and almost murdered his own family.

Meanwhile, details in the movie, such as the slime-oozing walls and Kathy overhearing daughter Missy talking to an imaginary friend she calls Jody—which the child draws as a pink pig—and then finding cloven hoof prints in the snow leading toward the water, were ripped straight from Anson's book.

The next-level theory is that Ronald was haunted by demonic forces first because 112 Ocean Ave. was perhaps built atop an American Indian burial site, and whatever got Ronald to kill almost got George to do the same. (Before The Amityville Horror, the "Indian burial ground" wasn't yet the horror trope it would become, though it's been endlessly recycled since—including when Stanley Kubrick placed the Overlook Hotel atop one in his 1980 adaptation of The Shining.)

Whether it was because the evil was just that potent or both men shared similar unflattering traits that made them susceptible to its powers remains part of the debate and the MGM+ series unearths new fuel for the fire, while simultaneously offering an explanation for a lot of what transpired on this earthly plane.

What happened to Ronald DeFeo Jr.?

As the years went by, Ronald told competing stories about what happened the night his family was killed. Most notably he alleged that his sister Dawn had killed their parents, brothers and sister and then he shot Dawn.

While pursuing a new trial, alleging he had ineffective counsel, he told reporters from prison in 1992 that the cottage industry borne from The Amityville Horror was why he was still behind bars. He said that his own attorney encouraged he go for an insanity defense because there was a better chance he'd go free one day and could cash in on book and movie deals.

"The whole thing was a con," Ronald said, "except for the crime."

His lawyer, William Weber, who sued for a share of proceeds from the book and 1979 film, alleging he had shared details about the house with the Lutzes, denied that his involvement with the various projects influenced the defense of his client in any way. (He settled his $60 million lawsuit for $2,500, according to the New York Times.) 

Weber said Ronald told him so many versions of what happened that he felt pleading insanity was the only way he could hope for an acquittal. Ronald reiterated his story that he only killed Dawn at his first parole hearing in 1999.

The panel determined that releasing him would be "incompatible with the safety and welfare of the community."

On the 2006 A&E special First Person Killers: Ronald DeFeo, forensic psychiatrist Dr. Steven Hoge said that, after interviewing Ronald for several hours, "he didn't find anything credible about the Dawn story." Rather, he added, "I wouldn't be able to say this was absolutely true, but it made me believe that, in fact, he had killed them."

Ronald spent most of the rest of his life at the Sullivan Correctional Facility in Fallsburg, N.Y., until he died at an Albany hospital in 2021 at the age of 69. And the why went with him.

Amityville: An Origin Story premieres Sunday, April 23, at 10/9c on MGM+

For more true crime updates on your need-to-know cases, head to Oxygen.com.