The detective leading the investigation into Gus Lamont’s disappearance says one of the four-year-old’s grandparents “remains a suspect”, as police conclude their latest search of the family’s remote outback sheep station.

South Australia Police on Thursday provided an update on what has become the state’s largest and most intensive missing persons investigations.

Major Crime Investigation Branch officer-in-charge Detective Superintendent Darren Fielke revealed that, following another three-day search of the sprawling 60,000-hectare property where Gus was last seen, they have not uncovered any new evidence “that helps us locate Gus”.

“You would appreciate, though, that it’s an ongoing investigation and there are some things that I’m still not able to say or make comment on due to operational reasons,” he said.

The little boy vanished from his grandparents’ Oak Park Station – a remote pastoral property about 43 kilometres south of Yunta in South Australia’s north-east – on September 27.

Supt. Fielke said that while there had been no breakthroughs in the case this week, investigators were continuing to focus on a single grandparent living at Oak Park Station, where Gus was reported missing almost eight months ago.

“One of the grandparents of Gus remains a suspect in this investigation,” he said during a press conference.

“Although at this time, I’m not prepared to elaborate any further in relation to that person, and I won’t take any questions in relation to that suspect.

“At this time, no other suspects or persons of interest have been identified in this investigation.”

The Nightly has sought responses from Gus’ grandparents, Josie and Shannon Murray, through their lawyers.

Following a SAPOL press conference in February, the couple issued a joint statement.

“We are absolutely devastated by the media release of SAPOL Major Crime,” it said. “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 Thursday police also revealed forensic examinations of items seized during January search warrants at the property – including a vehicle, motorcycle and electronic devices – had been forensically examined but failed to produce any new leads.

“No evidence has been located as a result of that testing that provides any further lines of inquiry that might assist us in relation to Gus’s disappearance,” Supt Fielke said.

“I can also say that these examinations have also not excluded anybody from the investigation either.”

Supt Fielke said more than 500 people have been identified as being around Oak Park Station on the day that Gus vanished.

“Task force members have been meticulously working through the list of those people and making individual contact with every one of those people,” he said.

“But all of the people that we have contacted so far have been discounted as being involved in any way in Gus’ disappearance, and as I said, there’s not many people left on that list, and we’ll continue to work through that.

“At this point in time, there is no evidence to suggest that Gus has been abducted.”

The update came after police spent three days searching the Murray’s property this week following recent heavy rain in the region.

Up to 17 detectives and specialist STAR Group officers searched more than 30 kilometres of waterways this week.

“Most of the searching on this occasion has concentrated around waterways, washaways, creek beds that have become exposed where vegetation has moved, where earth has moved as a result of the flooding,” said Det-Supt Fielke.

“This is the 11th time that Task Force Horizon or people associated with Task Force Horizon have been at Oak Park Station conducting a search.

“Unfortunately, we have not uncovered any other evidence that helps us locate Gus.”

Police also searched a number of bores and wells across the property during the operation.

“Again, unfortunately, without any success, but they needed to be done,” Det-Supt Fielke said.

AustraliaPolice swoop on property in search for Gus Lamont

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Police have previously said Gus was last seen playing outside the station’s homestead at about 5pm on September 27.

His grandmother Shannon Murray, who was caring for Gus and his baby brother Ronnie at the time, reportedly went to call him inside at about 5.30pm but could not find him.

Family members searched the property themselves before contacting police at about 8.30pm.

Officers arrived around 9.30pm and immediately launched a search operation, assisted by a helicopter using infrared technology but no trace of Gus was found.

The following day police intensified the operation, deploying trail bikes, ATVs, drones and SES volunteers across the rugged outback terrain surrounding the property.

Initially, investigators believed Gus may have wandered away from the homestead.

But in February, police dramatically declared Gus’ disappearance a major crime and publicly revealed investigators believed someone known to the little boy was involved in his disappearance and suspected death.

During a bombshell press conference, Det-Supt Fielke revealed investigators had ruled out both wandering off and abduction.

SA NewsGrandmother breaks silence six months after 4yo Gus vanished

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Police confirmed the investigation had narrowed its focus to a suspect known to Gus who lived at Oak Park Station, but stressed his parents Jessica and Joshua Lamont were not suspects.

“Task Force Horizon members are in constant contact with Gus’ parents,” Supt Fielke said today.

“They regularly speak, and they are regularly provided with updates in relation to this investigation.”

In February, Josie Murray was charged with unrelated firearm offences following a previous police search at the property.

But Acting Officer-in-Charge of Major Crime Detective Inspector Andrew Macrae stressed the firearm charges were not connected to Gus’ disappearance.

That same month, Jessica and Joshua Lamont broke their silence and issued an emotional public plea for information about their son.

“We are united in our grief and we are united in our search for answers about what happened to our little boy, Gus, who means everything to us,” they said.

“Our lives have been shattered and every moment without him is unbearable.

“We know someone out there may have information.

“If someone knows what happened, we are pleading with that person – or anyone who may have seen or heard anything – to please come forward.”

SA NewsNew footage emerges as parents of missing 4yo Gus speak out

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This week Supt. Fielke said Taskforce Horizon would continue searching for evidence with fresh aerial surveying to be conducted over a large area of the property.

“We have previously conducted aerial searching out to a 15km radius from the homestead, including the use of drones. All of the captured footage has been the subject of AI analysis,” he said.

“Much like this week’s ground search given the recent weather event, we are taking the opportunity to search this area again using the aerial platforms.

“This is will to occur in the coming weeks and once again, we will take advantage of AI technology to analyse the captured footage.

“If this analysis identifies new areas of interest, we will return to conduct further searching.”

Nearly eight months after Gus vanished, his body has still not been found and no one has been charged over his disappearance.

Supt. Fielke thanked the public for the overwhelming support and information provided to Taskforce Horizon. This has included 527 calls to Crime Stoppers, 65 emails, seven letters and 202 phone calls to police with information.

Anyone with any information on Gus Lamont’s disappearance is urged to contact Crime stoppers online at www.crimestopperssa.com.au or free call 1800 333 000.