Gus Lamont went missing in the South Australian outback in September. SA Police are now focused on his family

Oak Park Station, in South Australia’s Mid North region, is 45 kilometres from the nearest main road. The property, a sprawling sheep station about 350 kilometres north-east of Adelaide, is not signposted, and nor are there any indications of its location on nearby tracks. To end up at Oak Park, you have to be looking for it, or lost.

In summer, the days reach 40 degrees, and in winter, the nights drop below freezing. So vast and unforgiving is the landscape, that when four-year-old August Lamont, known as Gus, was reported missing there last September, no resource was spared to find him.

According to Gus’ family, the four-year-old was last seen playing in the dirt near the Oak Park homestead about 5pm on September 27. His grandmother, Shannon Murray, was at home caring for the boy’s younger brother while his mother Jessica Lamont and his other grandmother, Shannon’s partner Josie Murray, were tending to sheep several kilometres from the homestead, his family told police.

By the time Gus’ family reported him missing about three hours later, night was falling and concern was growing. There was no sign of the four-year-old; he had vanished.

On Thursday, police declared Gus’ disappearance and suspected death a major crime after identifying a person living at Oak Park and known to Gus as a suspect in the investigation. Gus’ mother Jessica and his father, Joshua Lamont, who does not live at Oak Park, are not suspects in their son’s disappearance.

“We don’t believe now that Gus is alive,” Detective Superintendent Darren Fielke, the officer in charge of SA Police’s Major Crime Investigation Branch, said.

Over the weeks that followed Gus’ disappearance, SA Police launched an unprecedented missing persons search. Combined parties of almost 400, including police officers, State Emergency Service volunteers, Australian Defence Force personnel, members of the local community and Indigenous trackers painstakingly combed the property. Searchers scoured the red dirt for clues; they looked under thick shrubs, and searched day after day for any sign of the curly headed, wide-eyed boy.

Several buildings at Oak Park were searched top to bottom, six disused mine shafts were checked and cleared, dams were dived into and drained, and drones and aircraft were used to search a 706-square kilometre area around the station. Search parties scouring the property on foot examined a 95-square kilometre area over eight separate searches across 20 days. None located Gus or any signs of him.

“No stone has been left unturned,” Fielke said.

Initially, investigators were told Gus’ family believed the four-year-old had “wandered off” and was lost somewhere on the property. Almost immediately, though, something seemed amiss; the searches had been thorough in terrain unlikely to be able to hide a body, even that of a small boy.

“At this time, despite all of the combined search efforts, we have found no evidence, physical or otherwise, to suggest that Gus has merely wandered off from the homestead,” Fielke said.

By the time police officially launched Task Force Horizon, the large-scale operation to find Gus, on October 14, investigators had already started quietly following two other lines of inquiry: that Gus had been abducted from Oak Park in the short window that he was left alone, or that someone known to him was involved in his disappearance and suspected death.

Fielke said police had not uncovered any evidence to suggest Gus had been abducted from the remote property after devoting significant resources and time to investigating the theory. No people aside from those living at Oak Park had been seen in the area when Gus disappeared, and nor had any “foreign” cars or tyre tracks, Fielke said.

“The opportunity for anyone to abduct Gus is extremely low,” Fielke said.

“The timing of being in the area when Gus was playing outside would need to be impeccable.”

Detectives spoke to several people in South Australia’s Mid North with “a risk profile associated with abduction or child offending”. “Those people have been discounted,” Fielke said.

Neighbours, workers at Oak Park and neighbouring stations, and people in the area at the time of Gus’ disappearance have all been discounted as suspects. “Through all of this effort, we have found no evidence to suggest that Gus was abducted from the property,” Fielke said.

Over the course of several interviews with residents at Oak Park, investigators noticed discrepancies in the timelines and versions of events they had initially given police.

“We’ve been looking at information almost right from the start,” Fielke said. Detectives are investigating whether Gus died by misadventure and his body was moved, or if he was intentionally killed.

Last month, detectives, armed with a search warrant, returned to Oak Park, where they questioned the residents, who until then had been unaware they were under suspicion.

During that visit, on January 14 and 15, they provided investigators with further information that police say was at odds with their previous statements. Fielke said a detailed review of the information provided since Gus’ disappearance identified a “number of inconsistencies and discrepancies”.

“It’s very delicate,” Fielke said.

“We have a suspect who we believe is known to Gus. Task Force Horizon members [and] myself are very cognisant of how delicate that is, and what that means for the family.”

During the visit, detectives searched the Oak Park homestead and seized a car and a motorcycle – both vehicles “of interest” that had been used on the property – and several electronic devices, including mobile phones, computers and iPads for forensic testing. Shortly after, someone known to Gus withdrew their co-operation and is no longer assisting police, Fielke said.

In a statement issued on Friday afternoon, Gus’ family said they were “absolutely devastated” that the boy’s disappearance and suspected death had been declared a major crime.

“The family has co-operated fully with the investigation and want nothing more than to find Gus and reunite him with his mum and dad,” they said.

Since the disappearance, police have been inundated with information from the public, including calls to Crime Stoppers, emails and letters.

“The information has been overwhelming at times, but it has been valuable,” Fielke said. In the early stages of the investigation, since-discredited theories were rife on social media as speculation swirled online and in the local community about what had happened to Gus.

Fielke did not rule out conducting further searches at Oak Park or other areas should investigators receive new information, or making an arrest over Gus’ disappearance.

“We will continue to thoroughly and meticulously investigate the disappearance of Gus until we get an outcome,” Fielke said.

“We are all focused and determined to locate Gus and return him to his parents. Nothing is off the table as we work towards that outcome.”

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