Police have returned to the home of missing four-year-old Gus Lamont to search for new evidence after identifying a suspect in his disappearance.

Gus (short for August) went missing on 27 September 2025 from his family’s remote sheep station, sparking one of the biggest and most intense searches in South Australia’s history.

He had been playing outside at 5pm but, when his grandmother went to call him inside half an hour later, he was gone, police were told.

Based on information from people living with Gus at Oak Park Station, SA police initially believed he had wandered off.

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Drones, divers, dogs and teams of volunteers, police, emergency services and defence force personnel searched the 60,000-hectare property, which is about 300km inland from Adelaide, and beyond.

After advice from survival experts, the hope of finding Gus alive dwindled, and the search became a recovery operation.

Police had consistently said there was no evidence of foul play, though they could not rule anything out, and that the family was cooperating.

But police announced on 5 February that the case was now considered a major crime, alleging that the suspect was someone who lived with Gus, and that they had seized a vehicle, a motorbike and electronic devices in mid- January.

Det Supt Darren Fielke, the officer in charge of major crime, said police had “identified a number of inconsistencies and discrepancies” in the information family members gave them.

“As a result of these inconsistencies, and investigations into them, a person who resides at Oak Park Station has withdrawn their support for the police and is no longer cooperating with us,” he said.

“The person who has withdrawn their cooperation is now considered a suspect in the disappearance of Gus.”

Police had been working on three theories, Fielke said: that Gus had wandered off, that he had been abducted, and that someone known to him was involved with his disappearance.

Their investigations found the first two options were unlikely, leaving them with the third option.

Fielke stressed that the suspect was not one of his parents.

Gus’s two grandmothers released a statement through their lawyers, saying they were “devastated” that the case was now a major crime, that the family has “cooperated fully with the investigation and want nothing more than to find Gus and reunite him with his mum and dad”.

On Monday, police said Task Force Horizon detectives will return to Oak Park station and will be there for at least two days.

“Members attached to Task Force Horizon conducting inquiries into the disappearance of four-year-old Gus Lamont on 27 September 2025 have returned to Oak Park Station to continue searching for evidence,” Sapol said in a statement.

“It is anticipated that Task Force Horizon detectives will remain in the area for at least the next two days.

“An update on the search activities will be provided as they progress.”

Anyone with information should contact Crime Stoppers on 1800 333 000.