Police say they are confident they have done all they can in the search for missing four-year-old Gus Lamont and have revealed a footprint found in the search last week is now deemed unrelated to the investigation.

Gus was last seen playing on a mound of dirt about 5pm on Saturday, September 27 by his grandmother at the family’s Oak Park Station homestead, about 43km from the town of Yunta in South Australia.

By 5.30pm, Gus – who has been described as shy but adventurous – had vanished and a full-scale ground and air search of the property and surrounding area was launched.

SA Police Assistant Commissioner Ian Parrott said the search for Gus would be scaled back from today and the investigation would be managed by the Missing Persons Investigation Section.

“We are confident that we have done all we can to locate Gus within the search area,” Parrott said.

“Despite our very best efforts to find Gus we have determined that the search will be scaled back from this afternoon.”

Parrott said no evidence had been recovered in the search for Gus, despite earlier reports of a small boot footprint found 500 metres from the property.

“At this point, no trace of Gus has been located,” he said.

“No tangible pieces of evidence, such as footprints, a hat or clothing, have been located to identify any direction of travel to assist searchers.”

SA Police Deputy Commissioner Linda Williams confirmed the boot footprint has since been found to be unrelated to the missing four-year-old.

A “significant” aerial search using special drones with infrared technology was used on Friday and Saturday.

It is the same technology police used in the search for the remains of Julian Story in Port Lincoln.

“It’s quite complex technology, so the results will take some time to work through, but police will investigate any findings through further searches,” police said today.

Police said officers may return to the property once the results of the drone mission are finalised.

Over the past 48 hours, the search for Gus shifted to a recovery mission.

Police spoke to the family last week to prepare them for the grim likelihood Gus has not survived.

“On Tuesday night senior police spoke to Gus’ family and prepared them for the fact that Gus may not have survived due to the passage of time, his age and the nature of the terrain he is missing in,” Parrott added.

“This assessment was based on medical evidence from a doctor who is recognised by the Australian rescue authorities as an expert opinion on time frame for survival.

“While those involved in the search have been hoping for a miracle, over the past 48 hours the search has shifted to a recovery operation.”

Police continue to investigate Gus’ disappearance and are working to rule out every option.

A public appeal remains in place for anyone with information.

“If anything is any information comes that directs us to conduct further searches in specific areas, we will be doing that in the coming weeks,” Williams said.

“As we’ve stated, we will never give up hope of finding Gus.

“There are further lines of inquiry being undertaken and the family have continued to cooperate fully with police and have consented to every request that we have made of them thus far.”

An average of 30 SES volunteers have taken part in the search for Gus each day.

The Australian Defence Force (ADF) also provided 50 personel for two days to assist police.

Before it was scaled back, the search for Gus spanned seven days and an area of almost 500 square kilometres, involving aircraft and teams on the ground.