A new search for a missing four-year-old boy is about to ramp up months after he vanished from his family's remote outback farmhouse.
Gus Lamont was last seen by his grandmother in the late afternoon of September 27, playing on a mound of dirt outside a sprawling sheep station in South Australia's Mid North.
He has not been seen since.
Intensive searches comprising hundreds of team members, spanning 470sq km and involving aerial support as well as mounted units, have all failed to find the young boy.
A renewed search will begin on Tuesday, focusing on six mine shafts near the Oak Park Station area.
The search is expected to last up to three days and will involve officers from STAR Group and Task Force Horizon, who will use specialised equipment to search the mines, police said in a statement on Monday.
The uncovered and unfenced shafts are located between 5.5km and 12km from the Oak Park homestead in areas not searched on foot by police.
Police said they were not previously aware of the location of the sites.
Deputy Police Commissioner Linda Williams said the force would not stop searching until every avenue had been explored.
"These searches will either locate evidence or eliminate these locations from further investigation by the task force," she said.
Police drained and searched a dam in late October, ruling out the possibility Gus drowned on the property.
It took SA Police about three-and-a-half hours to drain 3.2 million litres of water from the 4.5m-deep dam, which is 600m from the homestead.
"Police divers have thoroughly searched the main dam and the holding dam, including clearing of weed beds, however, there was nothing of significance found," police said in a statement.
The water was then pumped back into the dam.
An initial 10-day air and ground search at the property, about 40km south of Yunta, was one of the largest undertaken by SA Police.
A four-day search within a 5.5km radius of the homestead earlier in October concluded without any evidence being located.
Police said further aerial imaging within a 10km radius of the homestead would take several weeks to complete.
Gus's family members have "continued to co-operate fully with police and are being supported by a victim contact officer", police said.
