Bone found in new search for Joanne Ratcliffe and Kirste Gordon who vanished from Adelaide Oval in 1973

Private investigators have made a shocking discovery on the first day of a renewed search for two girls who disappeared at Adelaide Oval over 50 years ago.

Private investigators have made a surprising discovery on the first day of a new search for two girls who vanished at Adelaide Oval more than 50 years ago.

A piece of bone believed to be a kneecap, was uncovered by a team exploring a farm site north of Yatina on Saturday, 7News reports.

The origin of the bone is still unclear and it’s been taken away for testing.

The private investigators are searching for the remains of Joanne Ratcliffe, 11, and Kirste Gordon, 4, who mysteriously disappeared from Adelaide Oval in 1973.

It’s always been believed they were abducted and murdered.

Today was the first of a two-day search at two mid-north sites between Jamestown and Orroroo.

The former home of Stan Hart where a previous search took place. Picture: Brett Hartwig

The two sites were named in handwritten claims by convicted pedophile Mark Trevor Marshall, who accused his own grandfather, Stanley Arthur Hart, of taking the children.

Hart’s farmhouse has already been searched by police but this new investigation will look at multiple sites nearby, which search organiser Bryan Littlely said have never been investigated by police.

The search team also examined a second site on Saturday, located significantly closer to Hart’s old farmhouse.

Hart, who died in 1999, was accused of the crimes by his grandson, convicted pedophile Mark Trevor Marshall, in a confession to the Mullighan Inquiry into abuse of children in state care.

Police spent three days excavating properties at Yatina, including one formerly owned by Hart and searching for remains of the girls in 2014.

Suzie Ratcliffe, sister of Joanne Ratcliffe. Picture: Tony Gough

Joanne’s sister Suzie Ratcliffe told The Advertiser that the new search gave her “renewed hope” that the case could be resolved.

“We’ve always continued to hold on to hope, that there’ll be answers,” Ms Ratcliffe said.

“We’ll never have closure, because that doesn’t exist.

“Once you answer questions, there are a whole new set of questions that will come forward.”

Originally published as Bone found in new search for Joanne Ratcliffe and Kirste Gordon who vanished from Adelaide Oval in 1973