The mother of the three missing Beaumont children has died without ever learning what happened to her daughters and son.
Nancy Helen Beaumont passed away aged 92 in an Adelaide nursing home on Monday.
The disappearance of her three children - Jane, 9, Arnna, 7, and Grant, 4 - on Australia Day in 1966 is one of the country's most enduring mysteries.
Their children never returned after leaving the family home for an afternoon at Glenelg Beach, sparking a widescale search operation that remains open today.
In 2013, investigators scoured a factory west of Adelaide after two brothers told police they had spent the 1966 Australia Day weekend digging a large hole on the site at the request of the owner Harry Phipps.
Phipps died in 2014 but his son, who accused his father of sexual abuse, believed he was linked to the missing children.
The factory site was excavated by police in early 2018 but only animal bones were found.
Despite the notoriety of the case, Mrs Beaumont and the siblings' father, Jim, retreated from the public eye and have not spoken to the media in decades.
Mr Beaumont is also aged in his 90s and living in Adelaide, but the couple separated years ago.
Mrs Beaumont's death notice said she would be privately cremated.
Australian Associated Press