The four-year-old was reportedly last seen playing on a mound of dirt at his family's Oak Park Station homestead nearly five months ago.
Police have returned to the property where missing boy Gus Lamont was last seen nearly five months ago as the investigation into his disappearance continues.
Gus, aged four, was last seen playing on a mound of dirt about 5pm on September 27 at his family's Oak Park Station homestead, located about 43 kilometres south of Yunta in South Australia.
Detectives from Task Force Horizon have kicked off a renewed search for evidence at Oak Park Station today, where they will remain for at least two days.
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"An update on the search activities will be provided as they progress," SA Police said in a statement.
Police earlier this month confirmed a person with close ties to the household, who is not one of his parents, had been speaking with detectives but then "withdrew cooperation" and has since been identified as a suspect.
Gus' disappearance is now being considered a major crime.
No arrests have been made.
Gus' grandparents Josie Murray and Shannon Murray released a statement through their lawyers, saying they were "absolutely devastated" by SA Police's statement on February 6.
"We are absolutely devastated by the media release of SAPOL Major Crime. The family has cooperated fully with the investigation and want nothing more than to find Gus and reunite him with his mum and dad," the statement read.
The lawyers also indicated they will not be making any further comments.
There is no suggestion Josie or Shannon Murray are involved in the disappearance of Gus and it is not unusual for anyone linked to an investigation to seek out legal advice.
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The search for Gus
No evidence of Gus has been uncovered despite extensive searches of the property, which Detective Superintendent Darren Fielke said has been the "largest and most intensive" missing person search ever undertaken by SA Police.
A full-scale ground and air search of the property and the surrounding area was launched after Gus went missing.
The search area has totalled 706 square kilometres, with the assistance of 80 Australian Defence Force soldiers, drones, mounted officers and aircraft.
Around 163 SA Police officers have been deployed for the search.
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A three-day search of six mine shafts near Oak Park Station also failed to uncover any evidence.
Police received more than 150 Crime Stoppers tips about the missing boy.
Officers returned to the area surrounding Oak Park Station to search for Gus' remains on February 2, but uncovered no evidence.
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