Jane Beaumont, nine, and her siblings, Arnna, seven, and Grant, four, disappeared during a trip to Adelaide’s Glenelg beach on Australia Day 1966.
The trio caught a bus together at 10am – with the seafront just five minutes away. But the kids never came home.
Following shock findings from a major new Seven News investigation, a possible gravesite has been located at a factory in Plympton.
The site was identified by two men, who revealed a former owner of the factory had asked them to dig a trench there days after the children went missing.
That man was Harry Phipps – a wealthy businessman who died in 2004.
He is now a principal person of interest in the case.
Insp Hutchins told assembled media on Friday afternoon that the eastern side of the dig site was 'pretty well clear' - and did not indicate it had been disturbed.
However the same was not true of the western side of the site - which was where 'the majority of the rubbish and bones' had been found.
He said police would continue to examine the area of disturbed earth on Friday afternoon.
Speaking earlier to media, Insp Hutchins said the search was ‘slow and methodical’.
‘This is a significant event in South Australia and we would love to solve it,' he said.
Here, New Idea takes a look at the notable revelations in the case that has haunted Australia for 52 years.
The mystery bather
Eyewitnesses on the beach the day the children disappeared pinpoint them playing under a sprinkler on the grass at 11am. Apparently the kids weren’t alone. A slim, blond man in a blue bathing suit was also present.
The man was lying on his front watching the three children play. A short time later, the kids were seen buying snacks using a one pound note. But they hadn’t left home with that much cash – leading to questions about who gave them the money.
What the postman saw
A local postman who knew the Beaumont children well said he spotted them at around 3pm on the day they disappeared.
According to the postman, the trio were walking away from the beach – alone – and seemed happy, even stopping to say hello to him.
Police trusted the postman’s account at the time, but officers believe he may have misjudged the time the event took place, with the encounter, in fact, happening earlier in the day.
A new witness
In March 1988, a woman came forward saying she had also seen the children with a man on the day they vanished.
The woman – who was 10 at the time – said she’d played with Jane Beaumont, until a man came to collect her and her siblings.
In an interview with New Idea, she said that Jane had pointed at him and said they had to go with him, before the siblings collected their things.
‘I was watching television at my godmother’s house when their photographs came on the news,’ she recalled.
‘I recognised them straight away as the new friends I’d made at the beach. I knew something had to be very wrong about them going away, but I really didn’t understand it all...’ she said.
The hoax letters
Two years after the kids disappeared, their parents Nancy and Jim received three letters. Two were supposedly written by their daughter Jane, and the other was from a man who claimed he had the children.
His letter said he’d appointed himself ‘guardian’ of the kids and was willing to hand them back.
But when Nancy and Jim drove to the designated meeting place, followed by a police officer, no-one arrived. Years later, forensic tests showed the letters were a hoax.
The new ‘gravesite’
A year-long investigation by Seven News, led by veteran journalist Michael Usher, has used state-of-the art technology to provide a significant breakthrough. The technology pinpointed a possible burial site at a factory in Plympton.
The area had been examined before, but inquiries suggest it was the wrong spot. An area of ‘disturbed earth’ measuring a metre wide, two metres long and two metres deep, was found – a spot as Usher puts it: ‘The size of a grave.’
The site was identified by two men, who revealed a former owner of the factory had asked them to dig a trench there.
That man was Harry Phipps – a wealthy businessman who died in 2004. But they didn’t make the connection until Phipps was named as a suspect.
‘The hairs on the back are standing up,’ one of those men, David Harkin, told Seven News.
Evidence from the suspect’s son
Phipps is described by Bill Hayes, a former SA detective, as ‘a predatory paedophile and dangerous man’, whose home was located just 250 metres from where the Beaumont children were last seen. In an interview aired by Seven News, Phipps’ estranged son Haydn claimed he saw the Beaumont children in the backyard of that home on the day they vanished.
‘Yeah, I seen them come in. They were lost and on their own and the description matched them identically,’ he said.