Police admit the search for answers has been exhausting and at times demoralising and concede "the longer this goes on, the closer we get to not finding him".
But they say their resolve to bring Gus home has not wavered.
Recent heavy rain offered a sliver of hope, drawing detectives and specialist officers back to the sprawling South Australian cattle station in the desperate hope swollen creeks and shifting soil might finally reveal a clue.
Instead, after three days of renewed searching, there is still no trace of the little boy.
Officers from Task Force Horizon began the latest search on Monday, targeting waterways, washaways and creek beds where rain and erosion could have moved soil or peeled back vegetation.
"Unfortunately, we have not uncovered any further evidence that helps us locate Gus," Major Crime Investigation Branch officer-in-charge Detective Superintendent Darren Fielke said on Thursday.
"We have invested a lot of time, a lot of effort, a lot of emotional energy into this.
"It's a tough job - it's relentless, it's demoralising at times - but we're not going to let up.
"We want to return Gus to his family."
Dams on the property have been searched and drained, but despite the scale of the effort, police have not found Gus, his clothing or any belongings linked to him.
Gus was last seen by his grandmother playing at the Oak Park Station homestead on September 27, 2025.
His disappearance, now declared a major crime, has sparked repeated searches across almost 500 sq km of harsh country, involving hundreds of police and volunteers, along with aerial support and mounted units.
The public has also thrown its weight behind the search, providing 836 separate pieces of information in eight months - 527 calls to Crime Stoppers, more than 200 to the police communications centre, over 60 letters and more than 60 emails, Det Supt Fielke said.
"It has all been followed up, it has all been investigated, and some of those inquiries have extended interstate."
Everyone spoken to so far had been ruled out and police have not found evidence to suggest Gus was abducted.
Attention continues to tighten around the family's remote station.
In January, investigators executed a search warrant at the homestead, seizing a vehicle, a motorcycle and several electronic devices for forensic examination.
"All of these items have been subjected to thorough forensic testing," Det Supt Fielke said.
"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' disappearance."
The results have also not excluded anyone from the investigation.
Gus' grandparents, Josie and Shannon Murray, continue to live at Oak Park and are represented by lawyers, with all communication through their solicitors.
"One of the grandparents of Gus remains a suspect in this investigation," Det Supt Fielke said, declining to give further details.
No other suspects or persons of interest have been identified.
In a public plea earlier this year, parents Josh Lamont and Jess Murray said they were united in grief and in their search for answers.
"Our lives have been shattered and every moment without him is unbearable," they said.
Gus' grandparents also released a brief statement through lawyers saying they were "absolutely devastated" someone at the station was a suspect.
Task Force Horizon and specialist officers have returned to Oak Park Station 11 times since Gus was reported missing.
Detectives concede the passing months could be closing the window on ever finding the little boy, but say they will keep going for as long as it takes.
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