A person linked to the disappearance of four-year-old Gus Lamont has been named as a suspect, prompting authorities to elevate the case to a major crime investigation.

Police have revealed that an individual residing on the property, distinct from Gus’s parents, initially engaged with detectives but has since ceased cooperation. This change in demeanor has led to them being regarded as a suspect.

As of now, no one has been detained in connection with the case.

Detective Superintendent Darren Fielke noted that investigators discovered “discrepancies” in the account of Gus’s last known activities.

“Due to these discrepancies and further inquiries, a resident of Oak Park station has stopped supporting the police efforts and is no longer assisting us,” Fielke stated.

“This individual’s withdrawal from cooperation has resulted in them being identified as a suspect in Gus’s disappearance,” he added.

“I do want to stress, however, that Gus’s parents are not suspects in his disappearance.”

Fielke could not provide further information on the suspect.

The “discrepancies” regarding information gathered from those at the property were identified in mid-January.

“Only as recently as 14 and 15 of January when we attended [the homestead], did we get more information that we have analysed and reviewed, which again has highlighted some discrepancies,” Fielke added.

A search warrant was executed at the Oak Park Station property at this time and a number of items were seized, including a car, a motorbike and electronic devices.

“I anticipate there will be further searches at Oak Park Station and at several sites on an adjacent national park to locate Gus as new information and intelligence comes to hand as the investigation continues,” Fielke said.

Only three people were on the property at the time of Gus’ disappearance, Fielke said.

He did not rule out the possibility of an arrest being made.

He revealed the investigation had centred on three theories – whether Gus was abducted, whether someone he knows was involved in his disappearance or suspected death and whether he did wander off from Oak Park Station.

Fielke said detectives from Taskforce Horizon have a “high level of confidence” he did not wander off.

Investigators have also found no evidence to suggest Gus was abducted.

He also confirmed Gus’ disappearance is now a major crime when providing an update to the media.

No evidence of Gus has been uncovered despite extensive searches of the property, which Fielke said has been the “largest and most intensive” missing person’s search ever undertaken by SA Police.

A full-scale ground and air search of the property and surrounding area was launched after Gus went missing.

Officers returned to the area surrounding Oak Park Station to search for Gus’ remains on February 2 but uncovered no evidence.

“The foot search has been unprecedented and the resources that have been used have been significant,” Fielke said of the search efforts.

“We’ve had deployments to Oak Park station for over 20 days as part of that operation and there’s been at least eight separate searches conducted.”

Fielke said the owners of Oak Park Station and adjoining properties had been conducting their owns searches.

Around 163 SA Police officers have been deployed for the search.

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.

“We’ve taken statements with the family, we’ve had to go through those statements with the family, and that’s just part of the normal investigational process that we go through,” Fielke said in January.

“We continue to engage with them.

“They went through a pretty horrid Christmas without Gus, and we check-in with the family regularly.”

Police previously stressed that no part of the investigation had turned up any suggestion of foul play.

Lamont was reported as last seen by his grandmother at the family’s Oak Park Station homestead.

About 30 minutes later, he had rerportedly vanished and a full-scale search was launched.

The four-year-old with blond curly hair was described as a shy but adventurous child.

His family have said in a statement they are “devastated” and “deeply distressed” by his disappearance.

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