An investigative taskforce has been set up more than two weeks since the disappearance of four-year-old Gus Lamont from an outback sheep station.

Police and Army personnel resumed scouring the harsh landscape on Tuesday in their search for the boy who went missing at the Oak Park Station homestead, about 40km south of Yunta in South Australia’s Mid North, on September 27.

The search radius has almost doubled from its original 2km zone surrounding the homestead. Police confirmed on Tuesday they would be looking an extra 2.5km to 3km further out.

Daily Mail was told at least 80 Australian Defence Force personnel joined police as they returned to the area in an apparent reverse of approach after the search had been scaled back on October 4. The State Emergency Service also joined the effort, many on all-terrain vehicles.

There is still no sign of Gus after he vanished from the front yard of his grandparents’ homestead. He was last seen playing in a makeshift sandpit about 5pm but was missing when checked on 30 minutes later.

The newly established Taskforce Horizon, made up of 12 specialists, will analyse all information from the search and provide advice on the ongoing operation.

As the search resumed, Daily Mail made an eerie discovery just 400m from his grandparents Shannon and Josie Murray’s house.

A meticulously maintained grave is partially hidden among a stand of scrub, behind a fence, with the cross-shaped headstone revealing a baby boy had previously perished in the area.

The grave of a small child is situated on the remote Outback South Australian property near to where young Gus Lamont vanished
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The grave of a small child is situated on the remote Outback South Australian property near to where young Gus Lamont vanished

The search for Gus was back in action on Tuesday with at least 80 Defence Force personnel joining the search
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The search for Gus was back in action on Tuesday with at least 80 Defence Force personnel joining the search

The boy went missing from the family's sheep station (pictured) located on dry, dusty and flat land in South Australia's mid north
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The boy went missing from the family’s sheep station (pictured) located on dry, dusty and flat land in South Australia’s mid north

It’s understood Shannon and Josie inherited Oak Park sheep station from Shannon’s parents, Vincent – a WWII prisoner of war – and Clair Pfeiffer.

On the headstone, under the words ‘My Jesus mercy’, the inscription shows that a John Smallacombe had passed away aged eight months in July, 1917.

It is not known if the child was an ancestor of Gus and his family.

Clair’s maiden name was Jones.

If Gus is somehow still alive, the property may one day be passed to him.

Gus’ mother Jessica and his one-year-old brother Ronnie also live at Oak Park.

His father Joshua Lamont resides two hours away in a ramshackle farmhouse in Belalie North, near Jamestown.

Gus’ family remain stoic and are co-operating with investigators, SA Police Commissioner Grant Stevens said.

‘But you can imagine how they’re feeling without having Gus or having answers as to exactly where he is and what’s happened to him. That would be traumatic for any family.’

SES searchers in their bright orange gear joined police and army in the new search
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SES searchers in their bright orange gear joined police and army in the new search

August 'Gus' Lamont was last seen on Saturday, September 27 at his grandparent's property about 40km south of Yunta
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August ‘Gus’ Lamont was last seen on Saturday, September 27 at his grandparent’s property about 40km south of Yunta

Gus was playing in a makeshift sandpit in the front yard when he went missing
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Gus was playing in a makeshift sandpit in the front yard when he went missing

Gus Lamont's family tree is seen above
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Gus Lamont’s family tree is seen above

A specialist task force is assisting the police, SES and army search effort
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A specialist task force is assisting the police, SES and army search effort

Gus' mother Jessica is pictured with the boy's father, Joshua Lamont, who is the frontman of Adelaide country band The Cut Snakes
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Gus’ mother Jessica is pictured with the boy’s father, Joshua Lamont, who is the frontman of Adelaide country band The Cut Snakes

All-terrain vehicles are seen being brought into the search area
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All-terrain vehicles are seen being brought into the search area

Commissioner Stevens added that there is no evidence Gus met with criminality.

‘Our focus is largely on an exhaustive search of the property, on the basis that Gus has wandered off, and we’re hopeful that we can find him and return him to his family.

‘But we also have an obligation to consider all possibilities, and that’s part of our work going forward, is to make sure that nothing is left unaddressed.’

He said the taskforce consists of search co-ordinator specialists, medical specialists and survivability specialists.

‘We are looking for up to two days… the resources that we’re deploying may change and the use of specialist drones will be another consideration.’

In a testament to the dusty, harsh terrain searchers are dealing with, some army vehicles briefly lost touch with their convoy amid a blinding shower of dust along the track between Yunta and Oak Park on Tuesday morning.

A media vehicle was also damaged in a separate incident.

Gus has long, blond, curly hair and was last seen wearing a grey sun hat, along with a blue T-shirt with a yellow Minion on the front, light-grey long pants and boots.