South Australia’s police commissioner has said two members of missing boy Gus Lamont’s family are “not cooperating” with investigators, as the search continues for the four‑year‑old who vanished in September.

Commissioner Grant Stevens told ABC Radio Adelaide on Wednesday that detectives continue to work closely with Gus’s parents, adding that “other members of the family” have withdrawn their support.

“As far as I’m aware, it’s status quo,” he said on radio.

“We are still working with Gus’s mum and dad and there are other members of the family who are no longer cooperating.”

A South Australia Police spokesperson confirmed to 7NEWS.com.au that “two family members are now only communicating via their legal representatives.”

Police first declared the case a major crime on February 5, revealing that a person who resides at Oak Park Station had stopped assisting investigators and was now considered a suspect.

Officers have repeatedly stressed that the suspect is not either of Gus’s parents, Josh or Jess Lamont.

Gus’s grandparents — Josie and Shannon Murray — issued a statement in February saying the family had “cooperated fully with the investigation”.

Police have not confirmed who are the two family members who have since ceased cooperation.

Nearly five months after their son disappeared, Josh and Jess Lamont released a statement on February 24, saying they were “united in grief” and begging anyone with information to come forward.

“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.”

“If someone knows what happened, we are pleading with that person — or anyone who may have seen or heard anything — to please come forward. Even the smallest detail could give us the answers we so desperately need.”

The family also released new video and another photograph of Gus, hoping it may jog someone’s memory.

They thanked police, emergency services, ADF personnel, volunteers, Indigenous trackers and supporters who have spent months searching the vast outback region around Oak Park Station.

“All we want is to bring Gus home and understand what happened to our beautiful boy,” they said.

Gus was last seen on September 27, playing outside the Oak Park homestead near Yunta while his grandmother cared for his younger brother inside, according to the family.

Despite one of the state’s largest search operations — involving SES volunteers, drones, helicopters, mounted officers and specialist trackers — no significant trace of the child has been found.

The only confirmed physical clue remains a single footprint discovered about 500m from the property.

Task Force Horizon detectives continue to pursue new leads, with police reiterating that “nothing is off the table”.