OAK PARK STATION, South Australia — Task Force Horizon detectives scoured abandoned mineshafts, underground tunnels and an outhouse at Oak Park Station this week. They found no evidence linked to the disappearance of Gus Lamont, the four-year-old boy missing since September 27.

The search targeted the 60,000-hectare property near Yunta, where Gus was last seen playing outside the main homestead. His grandmother had been inside caring for his younger brother at the time, according to police reports.

Officers examined numerous buildings and structures, including a remote section of the station and a water tank. Fresh cement in the outhouse drew scrutiny. A cadaver dog from New South Wales sniffed out potential human remains. A police helicopter provided aerial support.

No leads emerged. Detectives then shifted to Grampus, a property 24 kilometers away. Major crime teams combed the yard and homestead there. Again, nothing connected to Gus turned up.

“No evidence was located,” police stated after concluding operations at both sites. Investigators have not ruled out returning to Oak Park Station. The probe presses on.

Detective Superintendent Darren Fielke, who leads Major Crime, addressed the original timeline. Police arrived quickly after the alert on September 27 evening. Still, he said it’s possible Gus remained on the vast property when officers first reached the homestead.

“Yes, there was some time in between, but it is possible,” Fielke told reporters. “We’re still working on that original timeline.”

That timeline faces heavy review now. South Australia Police Commissioner Grant Stevens disclosed new friction Wednesday. Two family members have stopped cooperating with detectives.

“Gus went missing on the 27th of September and we still don’t have clarity as to exactly where Gus might be,” Stevens said. “It is fair to assume there is more work to be done. As with any major crime investigation, we don’t rest until we have a resolution.”

Stevens confirmed Gus’s parents continue to assist substantially. He declined specifics on the two who withdrew support.

Separately, one grandparent faces unrelated firearms charges. Josie Murray, who lives at Oak Park Station, will appear in Peterborough Magistrates Court on May 6. The charges stemmed from a police search of the Yunta homestead.

Stevens offered limited details. “I haven’t been briefed on the exact offences,” he said. “It is my assumption that they relate to either storage, ammunition, registration licensing.”

Under South Australia’s Firearms Act, police can enter properties with registered firearms or prohibition orders. Warrants cover other cases, Stevens explained. License holders must prove genuine need for their weapons.

Gus’s case draws intense focus on the isolated outback station. Task Force Horizon formed after initial searches yielded nothing. Detectives revisit sites and timelines amid family developments. No arrests tie directly to the boy’s vanishing.

Police urge tips from anyone with information. The four-year-old’s fate remains unknown seven months later.