In a stunning new lead in the decades old Beaumonts case - a chilling new video of a suspect has surfaced, less than a week after his death.
Members of Max McIntyre’s own family believe he was involved in Jane, Arrna and Grant’s disappearance and that they know where the children are buried.
"I know a lot about the Beaumont killings,” Max McIntyre said in an interview.
Investigative journalist Brian Littley said they asked McIntyre directly: “Were you involved, Max?”
“He said 'No, I wasn't but I'll tell you who was',” Mr Littley said.
Max McIntyre’s son Andrew McIntyre said he knows his father is part of the mystery.
"My father was involved in the abduction and murder of the Beaumont children,” Andrew said.
Could Max McIntyre hold the key to Australia's greatest criminal mystery?
Inside his home on a remote property on South Australia’s Yorke Peninsula, Max McIntyre opened up about the allegations that have dogged him for much of his life.
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"At the moment I'm researching the death of the Beaumonts. Because the only person that's going to clear my name is me,” he said on the video.
“I want the whole bloody mess looked at. Now, I'll get around to who killed the Beaumonts in a minute."
This never before seen interview, filmed in April 2015, is the only time he broke his silence.
On Tuesday last week, Max died aged 89 and, according to his son Andrew, he has taken the 50 year old secret to his grave.
While his father denied any involvement. Andrew McIntyre claims there was someone who may know what happened.
That person is his one time close friend, scout leader Anthony Munro.
Andrew first raised his own suspicions in a court case in 2008 after Max took out an injunction blocking he and sister from entering his property.
Since then he's had trouble finding anyone who would listen to what he told the court about his father and Munro.
"Now you want to know about Tony Munro," Max McIntyre said in the newly unearthed tapes with investigative journalist Bryan Littley trying to tease the story out of him.
Tony Munro had close relationships with numerous children through his scouting activities and a club he ran at Glenelg.
It was around the time that Jane, Arnna and Grant Beaumont disappeared from the same beach on Australia Day 1966.
Andrew McIntyre remembers that day it like it was yesterday.
"Our father told us he'd take us to the beach, but he changed his mind and left us home,” Andrew said.
He says when his father and Munro returned they were agitated and upset.
And there was sand and blood in Munro's car.
"The children were in the boot of his white (Ford) Zephyr,” Andrew said.
“My two sisters were taken to the boot and my sister had to brush the blood out of their hair and sand out of their hair."
His father never told him what had happened and how the children came to be in the boot of the car.
Andrew Mcintyre claims that two weeks after the Beaumonts disappeared, Munro drove him from Adelaide to his father's property in Stansbury on the Yorke Peninsula.
He says he dropped him in the driveway and sped off.
Andrew walked towards the house he noticed something had changed. The sinkhole at the back of the property had been filled in.
"Anthony Munro brought me over to Stansbury to point me in that direction... to see that the well had been filled in,” Andrew said.
Andrew said Munro told him “a flock of sheep had run down it. The sheep that'd lived on the property for years”.
He's convinced the Beaumonts are buried there and believes the authorities have an obligation to dig it up.
"My father liked to have his victims close handy,” Andrew said.
"He was a very cruel man, I've always been terrified of him. I have constant nightmares about my father.”
In 1990 Munro was jailed for abusing a child and later fled to Cambodia where he ran ladyboy bars.
With the authorities there on his tail, he returned to Adelaide last year and pleaded guilty to the abuse of two more boys in 1965.
One of those was Andrew McIntyre.
“It took a long time coming. It had to be dragged out of him,” Andrew said.
During this time, Munro was questioned over the Beaumonts but police say there's no evidence linking him to the case.
Andrew says that even if they were only responsible for the disposing of the bodies his father and Munro must have known who was involved in the abduction and murder
Andrew has been concerned that since Max's death his half-brother Danny has unwittingly destroyed some of their father's belongings
Danny McIntyre said the fires burning on the Yorke Peninsula property after Max McIntyre’s death were easily explained.
"Nah it's just wood mate. I'm not saying a word,” he told 7 News.
Asked if he thought Max was involed, Danny said: “Absolutely not.”
While police have investigated some of his claims, Andrew Mcintyre says they've stopped listening.
"[Andrew McIntyre] was a victim of Tony Munro in 1965 and 1966 at the time or around the time that the Beaumont children went missing,” Bryan Littley said.
“I think you've got to give him some credit. You can't believe half his story and not the rest of the story."
Certainly Max knew that Munro was abusing Andrew as he revealed in the Littley quote.
"I caught him in bed with my son. They were bundled and naked. I didn't make a scene,” Max said in the interview.
“He was a boy, a beautiful boy. He was my son and he was in love with a scout master."
Andrew Mcintyre says, while his father will never face justice, it's not too late for others involved to be caught and punished.
"All the evidence is out there. The witnesses are still alive and we'd like to come forward and tell our story,” Andrew said.