Investigations into the disappearance of siblings Jane, nine, Arnna, seven, and four-year-old Grant Beaumont led detectives to excavate a North Plympton factory site in 1966 following instructions from a Dutch clairvoyant, and again in 2013, but both searches proved futile.
Now, five years on, police have returned to a different area of the factory site to begin new excavations, following a review by SA Police's Major Crime Investigation Branch last year, combined with fresh evidence supplied by Channel 7, which conducted its own year-long investigation using never-before-tried technology.
The Channel 7 investigation identified an area of disturbed earth one metre wide, two metres long and two metres deep which hadn't been discovered previously. It is thought to be the potential grave site of the Beaumont children, 7 News reports.
Excavation commenced on Friday and is expected to last a few hours.
“We have our fingers crossed,” Detective chief inspector Greg Hutchin said on Friday, The Guardian reports. “We hope for the best but we do want to temper expectations.
“Clearly we have an anomaly which we need to investigate.”
The Beaumont children were assumed to be abducted and murdered, and were last seen playing with a man on the beach.
Local businessman Harry Phipps, who owned the factory in question and who died in 2004, is now the key suspect. His estranged son claims to have seen the Beaumont children in the backyard of their house the day they disappeared, 7 News reports - a home that was just 250 metres from the beach.
"He was a paedophile. He was a predatory paedophile," Former South Australia Police Detective Bill Hayes told 7 News. "He was a dangerous man, we know that."
This week, a woman also came forward with explosive allegations that she was sexually assaulted by lead suspect Phipps in 1979.
The woman, referred to as Linda, has told Channel 7 that she encountered Phipps when she was 14-years-old and heading home from a friend’s house. She was dressed in her school uniform at the time.
“He just walked me across the road and was just saying that, you know, you’re a really pretty girl, I’ve seen you around and I just went with him,” she told Michael Usher in an investigation set to air at 9pm on Wednesday.
“He wasn’t horrible; he wasn’t nasty."
Linda says she followed the man to a vacant block but it was there his demeanour shifted.
“It was really terrible, he sorta started getting really slimy, really dirty talk and things like that,” she alleges.
Linda said that Phipps then sexually assaulted her, a horrifying incident that she “couldn’t tell anyone because I was too scared of them telling my father.”