Earlier in the day, police found bones belonging to a 'horse or a cow'.
Officers bagged items found on the western side of the dig, however police were quick to say that the evidence was confirmed, by a forensic anthropologist, to be animal remains not human bone.
'We've found a number of non-human bones. They are from a large animal, similar to a horse or a cow,' Chief Insp Greg Hutchins said at around 4pm on Friday.
'We've also found quite a bit of rubbish. Clearly we are in disturbed soil.'
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 was located.
Compelling information from a year-long probe has led police back to part of a factory in Plympton, where it was believed the children’s bodies may lie.
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.
Speaking to media at around 1pm on Friday, 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.
But tragically, the mystery of what happened to the three Beaumont children remains.
Det Sup Des Bray said that police have some further enquires to do with regard to Harry Phipps - but that they did not have 'any proof that he's involved'.
With the case still wide open, New Idea takes a look at the notable revelations in the mystery 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, used state-of-the art technology to provide a breakthrough. The technology pinpointed a possible burial site at a factory in Plympton.
The area had been examined before, but inquiries suggested it was the wrong spot.
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.
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.
But with the most recent dig site showing no sign of the missing children, what happened to them remains a mystery.