In House of Terror, the unusual and harrowing deaths of Agnès Dupont de Ligonnès and her four children were examined.
They were found under their house porch and the main suspect - husband and father Xavier Dupont de Ligonnès - has been missing since
Since the gruesome discovery, Xavier has been the subject of an international arrest warrant and was last seen alive on CCTV in April 2011, near a budget hotel in the south of France where he abandoned his car.
The internet has been sent into a frenzy, with many people speculating about sightings and theories behind the harrowing story.
Recently, the show's creator Terry Dunn Meurer revealed he'd been "spotted" in Chicago, and the director Clay Jeter has hinted at hundreds of reported sightings.
And the director for the episode, Clay Jeter, revealed unseen evidence on the case, including how Xavier spoke to his wife about "mass suicide".
Here is everything we know about the theories surrounding the Dupont de Ligonnès' disappearance.
Who is Xavier Dupont de Ligonnès?
Xavier Dupont de Ligonnès was the son of Bernard-Hubert Dupont de Ligonnès, an engineer with a degree from the École nationale supérieure de mécanique et d'aérotechnique in Poitiers.
His mother was Geneviève Thérèse Maître and he was born on January 9, 1961, in Versailles.
The Ligonnès family is an old aristocratic French family, from Annonay in the Vivarais region in south-eastern France.
Not much is known about Xavier’ Dupont de Ligonnès personal life.
He was a salesman and businessman and was once the CEO of a company named SELREF, based in Pornic, south-east France.
Xavier married Agnès Hodanger in 1992 and they were together until she died in 2011.
When Xavier and Agnès got together, she had another son, Arthur Nicolas, from a previous relationship. However, Arthur was brought up as Xavier’s child and they married when he was two-years-old.
Xavier and Agnes then had three children together: Thomas (aged 18 at time of death), Anne (16) and Benoît (13).
Is Xavier Dupont de Ligonnès dead?
One of the main theories behind Xavier Dupont de Ligonnès' disappearance is that he killed himself after murdering his family.
In 2013, French police stopped looking for his body, with Prosecutor Brigitte Lamy saying that she believes that he committed suicide and adding: "We will be sure of it the day we discover his body."
Ever since, multiple bodies have been found around the area Dupont de Ligonnès was last seen. In 2013, a body was found in Cogolin, but police confirmed it was not him, while in 2015, a walker found bones in Bagnols-en-Forêt along with a survival camp of a lighter, glasses, sleeping bag, empty wallet and a bill from 2011.
However, police compared Dupont de Ligonnès' DNA with DNA obtained from the personal effects found around the bones and determined that there was not a match.
Unsolved Mysteries director Clay Jeter recently spoke out about one "significant" point in Xavier Dupont’s personality that could be key to the case.
Speaking on the podcast, You Can't Make This Up, he said: "It's really significant to understanding how the expectations of his life matched up with the life he was living – the American dream fell into this. He was an entrepreneur, now he’s gone to the epicentre of capitalism in the world, America. To prove to everyone that he really is excellent, America makes sense. Of course, he goes to America and it doesn’t work out like that."
What are the latest theories surrounding Dupont's disappearance?
Since the documentary dropped on the streaming site, there has been a lot of interest in Dupont's disappearance and whereabouts with new theories coming out daily.
Theory one: Xavier was "framed"
One of the latest theories is that Xavier may have been "framed".
Clay Jeter says he spoked to Xavier's family lawyer Stefan Goldenstein, who doesn't believe he could have done it.
Jeter said: "I'm speaking to Stefan Goldenstein - his family's lawyer, who represents his sister, her husband and Xavier's mother. He would say, 'He wouldn’t have done this, because he has no motive. He couldn’t have done this, because he doesn't have the skills to have pulled something like this off.'"
In the documentary, the area where the graves were dug underneath the terrace is very low. Therefore Jeter says "It would be a tonne of physical labour to remove this soil to remove that much soil."
Xavier also reportedly had a bad back, with Jeter adding: "There's just no way he would have been able to do that himself."
This has raised the question, of who could have possibly committed the crime.
Jeter continued: "One theory is that Xavier was caught up in some stuff that we don't really understand and the letters that Xavier wrote, these were all forced and actually there were professional killers, who did all of this - killed Xavier's family and later killed him and framed Xavier for the murder of his own family. Really this was just something Xavier was caught up in his maybe financial desperations and that's how that all came to pass.
"We don't know who these players are or what their motivations were, but it's one idea of how this could have been done so professionally and still explain the disappearance of Xavier - that he actually was murdered, but he was murdered away from the home in a way that was designed to look like he had killed them and gone on this road trip and disappeared and run off."
Theory two: The case is a "cover story for something else"
Another theory Jeter pointed out relates to the mysterious letter from Xavier, claiming he was a U.S. secret agent who had entered the witness protection program, and another letter his children's private Catholic school received, explaining they were moving to Australia.
Jeter says when the autopsies were done one the bodies, "There was no visual identification" to confirm who the bodies were.
He explained in the You Can't Make This Up podcast: "The other theory that is even more outlandish - when the autopsies were done on the body, it was pretty obvious to everyone involved that we were missing a mother and four children and two dogs, and low and behold, here's a mother, and four children and two dogs. They roughly matched ages and genders, so there's no real need to go and dot every i and cross ever t on this, because it's kind of obvious what happened here.
"So, [it was like] 'Let's wrap this up quickly, let's move on, let's allow these bodies to be buried very quickly, and let the family get some peace.' But in that process, there was DNA evidence which suggested that the bodies which were found were all related to each other, but there was no actual evidence which said this actually is Arthur, Agnes, Thomas, Binuar, Anne. There was no evidence on specifically who they are."
Jeter brought up a "conspiracist" theory, which stated that the bodies were "kept away."
"There was no visual identification," he explained. "They kept the family out presumably because these bodies had been buried for a while and they don't look so good. But the conspiracy theory might say, 'They were kept away' They weren't brought in, there was no visual identification. And a couple days later they were buried. And it wasn't until later that we said, 'Did we mess something up here, should we have done a little bit more?'
"Again, that is pretty farfetched, but the idea is, 'Ok if it's not them, who is it?' And in that scenario, whether it was actually the DEA or something else similar, Xavier was kind of telling the truth in that letter, and he and the family are off in hiding somewhere and there was a whole system that helped them with this escape and planted these bodies, and the cover story is that Xavier murdered his entire family."
Theory three: Xavier told Agnes he wanted a "mass murder"
During his appearance on the You Can't Make This Up podcast, Jeter said Xavier had told his wife Agnes he wanted a "mass murder".
"Agnes was very religious," he said. "Xavier was theoretically religious. Agnes had been posting stuff on some forums and expressing to people in these smaller communities the issues she was having with Xavier and the relationship they were having. Xavier told her, 'All of us dying in a mass suicide would not be the worst thing for us'."
The director also suggested a potential motive for Xavier, saying: "You can follow along someone’s head space but it’s very difficult when they go ahead with it. I do think in Xavier’s mind he believed that he was saving them from a life of embarrassment, a life of shame which is just the worst possible thing for him."
Theory four: Xavier's case shares link to past murder
To assist with the huge interest, Netflix recently released a series of unseen video clips and interviews on each of the six cases including the Xavier Dupont de Ligonnes story.
With an international arrest warrant to his name for nearly a decade, many now doubt if Dupont will ever be found. But not journalist Anne-Sophie Martin, a key voice in the House of Terror episode.
“In the United States there is a much-cited case that resembles the Ligonnes case in a fascinating and disturbing way,” she says, explaining how List, a struggling accountant living in a well-off neighbourhood, killed his family over the course of a day in November 1971 before disappearing completely.
However, on 1st June 1989, List was finally caught by law enforcement.
“They found list because of a TV show,” explained Martin. “On this show [America’s Most Wanted] they used age-enhancing software to age John List’s face, so as to show what this fugitive might look like who had been on the run for 18 years.
“There was a woman who saw it who said: ‘That’s my neighbour!” And it was her neighbour.”
Where is Xavier?
According to Jeter, there have been hundreds of sightings of Xavier, with people claiming to have seen him "everywhere".
"When this came to light in 2011 it was huge. I think they have documented 800-900 sightings of Xavier in the last decade? People are seeing Xavier everywhere," Jeter explained.
"I have to hope it’s possible. That’s what motivated the producers of this show. Looking at Netflix and the reach it has, it’s so vast, you just never know."
Is Xavier Dupont de Ligonnès in France?
According to newly released clips, there have been over 1000 reported sightings of Dupont - many which claim to have spotted Dupont in his local area.
In an exclusive clip posted in a file on the streaming site's Reddit page, Dupont's former neighbour Estelle Chapon says that she often looks for him.
"When I'm in a crowd, I look for him. It's an urge too big to resist," she explained.
However, Martin says that she doesn't believe Dupont would hide out in France, saying it's an "insult to Xavier's intelligence".
"In the case of Xavier, there are more than 1,000 reported sightings. These are people who believe they have seen Xavier Dupont de Ligonnes a little bit anywhere: on a bus, on a cafe patio, in a restaurant, at a tool booth, or in a crowd. There were many at first when his image was first being shown," Martin explained.
"Most of these sightings are in France, which I think is an insult to Xavier's intelligence to think that he would stay in the country. Because he's also not the type to do plastic surgery so as to pass unnoticed. So you know I think he's alive and living very far aware from here."
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Is Xavier Dupont de Ligonnès in hiding in another country?
Other theories suggest that Dupont de Ligonnès has been on the run since murdering his family due to the methodical way in which his family were killed and the way it was potentially covered up.
The lease on the family home had been terminated, all banks closed, friends and family were told via letter that the Dupont De Ligonnès were emigrating to Australia.
Since 2011, French police have received over 900 possible sightings of Dupont de Ligonnès and in 2015, a Nantes journalist received a picture of his sons, Arthur and Benoit, with a handwritten note which read: "I am still alive."
Some believe that Dupont de Ligonnès is laying low in France, with there being numerous reported sightings of him in the country. In 2016, police began a manhunt for the murder suspect after his likeness was picked up on a casino's CCTV camera in Neris-les-Bains.
Two years later, police raided a monastery in the village where Dupont de Ligonnès was last seen after several church-goers reported seeing him. They soon determined however that the person spotted was actually a monk who looked like the aristocrat.
Another potential theory involves Dupont de Ligonnès fleeing to South America, as Martin mentioned in Unsolved Mysteries that he knew enough Spanish and English to start a new life in the country. Dupont de Ligonnès friend Bruno de Stabenrath also believes this theory.
However, according to The Sun, police believe that Dupont de Ligonnès may have undergone plastic surgery and started a new life in Scotland.
In October last year, a man on a flight from Paris was arrested at Glasgow Airport after Interpol informed that a passenger was using a stolen passport to travel. However, the arrested man was confirmed not to be Dupont de Ligonnès and released without charge.
While it doesn't seem as though there are currently any concrete leads as to Dupont De Ligonnès' location, there's no doubt that viewers of Unsolved Mysteries will now be on the lookout.