Grant Alfred Beaumont, the father of the three Beaumont children who went missing in Adelaide in the 1960s, has died, aged 97.
The disappearance of Jane, Arnna, and Grant Beaumont on Australia Day in 1966 became one of the country's enduring mysteries and remains unsolved.
The children — aged 9, 7 and 4 — left their Somerton Park home for a day at Glenelg beach, but never came home.
A funeral notice published on Saturday said Grant — also known as Jim — was "reunited in heaven" with his children.
He died on April 9.
Mr Beaumont reported his missing children to Glenelg Police just before 7:20pm on January 26, 1966, and helped police conduct a thorough search of the beach area.
Later that night, he authorised police to supply local radio stations with public announcements to help locate the children.
Former South Australian victims of crime commissioner Michael O'Connell told the ABC Mr Beaumont lived with decades of "unresolved grief".
Mr O'Connell, who worked with the family, said Mr Beaumont was a private person and kept his emotions to himself.
"Since the Beaumont children went missing, there's been much conjecture, innuendo, even hoaxes in relation to those children, their whereabouts and what happened to them," he said.
"It's a mystery, and it's a mystery that appears not to be readily solved."
At the time the children went missing, several witnesses told police they had seen them with a tall, thin-faced man with short, blond hair.
A composite sketch of the suspect was released with hopes of identifying him.
Volunteers helped police in what was the largest scale search in South Australia's history.
Glenelg beach was scoured, drains were flushed and hundreds of witnesses came forward.
On the 50th anniversary of the children's disappearance in 2016, police put out a renewed call for information on the case.
They received hundreds of calls within the first few months and investigated at least 37 people of interest.
In early 2018, police conducted a dig at an Adelaide factory site hoping to find remains of the missing children.
The dig was prompted by two brothers who told police they had once dug a hole for the factory's owner, Harry Phipps, who was a person of interest in the Beaumont case.
The children's mother and Mr Beaumont's former wife, Nancy Beaumont, passed away on September 16, 2019, aged 92.
