One of the nation's most high-profile former detectives says he's confident South Australian police won't lose hope in the search for four-year-old Gus Lamont.

Authorities have been conducting extensive searches of the remote area around Yunta, in the state's Mid North, focusing on the possibility that the child wandered off.

Gary Jubelin, a former detective who led the investigation into the 2014 disappearance of William Tyrrell in NSW , has offered his take on Gus's disappearance.

"A three- or four-year-old child, you can't turn your back on them, so it's rare they disappear like this," he said.

"90 per cent of times the child is found, it's these rare situations where there are no answers and that creates a mystery," he added.

South Australian police are exp

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