South Australia's top cop is "absolutely certain" police will revisit the remote homestead where Gus Lamont was last seen, with police vowing to continue searching for missing toddler until there is a "breakthrough" in the case.
The four-year-old was last seen playing on a dirt mound at his family's property Oak Park Station in South Australia around 5pm on September 27.
There has been no sign of Gus for more than six months, despite the search being the largest and most intensive missing person investigation in the state's history.
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SA Police Commissioner Grant Stevens told reporters today he is "absolutely certain" that detectives will return to Oak Park Station as part of the ongoing investigation, adding that he is confident that Gus will one day be found.
"We are not going to step away from this investigation until we have some outcome for the family," Stevens said.
"I think we've demonstrated over time that the resolve to bring these types of major investigations to a conclusion never stops.
"I am confident that level of effort will continue to be applied in the hope that we get a breakthrough."
He said the majority of the searches had taken place "in and around the property".
The most recent search for Gus was called off on March 12 after no evidence was uncovered.
Last month, the top cop claimed that two members of the missing four-year-old's family had been "not cooperating" with authorities investigating his disappearance.
"We are still working with Gus' mum and dad and there are other members of the family who are no longer cooperating," Stevens told ABC Radio Adelaide.
SA Police claimed to nine.com.au that two of Gus' family members are "only communicating via their legal representatives".
It is not known which family members have allegedly withdrawn cooperation with investigators.
SA Police declared Gus' disappearance as a major crime in February and claimed that a person with close ties to the household, who is not one of Gus' parents, had been previously speaking with detectives but allegedly "withdrew coperation".
Police said that person was considered a suspect, though their identity hasn't been revealed.
Josie Murray and Gus' other grandparent Shannon Murray released a statement through their lawyers, saying they were "absolutely devastated" by SA Police's statement on February 6.
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"We are absolutely devastated by the media release of SAPOL Major Crime. The family has cooperated fully with the investigation and want nothing more than to find Gus and reunite him with his mum and dad," the statement read.
There is no suggestion Josie or Shannon Murray are involved in the disappearance of Gus and it is not unusual for anyone linked to an investigation to seek out legal advice.
Police charged 75-year-old Josie Murray with firearms offences in February but have maintained the charges are not linked to the toddler's disappearance.
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Police earlier confirmed they had "all but ruled out" the possibility that Gus had simply wandered off.
"There has not been one single piece of evidence that we have located during that searching exercise, the most extensive search I think arguably in the history of South Australia, that has given us any indication that he did wander off," Stevens said.
He insisted that finding Gus was the main concern of the state's police force, saying he wished to bring closure to Gus' parents, Josh and Jess.
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