Detectives combed through derelict structures on the 60,000-hectare Oak Park Station property near Yunta, South Australia. They peered into underground tunnels and old mineshafts. Crews checked a water tank and an outhouse where fresh cement had been poured recently. A cadaver dog from New South Wales sniffed for human remains. A police helicopter hovered overhead.

No clues turned up. The search extended to a nearby property at Grampus, 24 kilometers away. Major crime investigators sifted the yard and homestead there too. Again, nothing linked to Gus Lamont’s disappearance.

“No evidence was located,” police stated after concluding the operation. Detectives haven’t ruled out going back. The investigation presses on.

Gus vanished on September 27. Relatives told officers he was playing outside the main homestead while his grandmother watched his younger brother inside. Police arrived quickly that night. Detective Superintendent Darren Fielke, who leads Major Crime, said it’s still possible the boy was somewhere on the vast property then.

“Police were on scene quite quickly when they were advised that Gus was missing,” Fielke said. “Yes, there was some time in between, but it is possible. We’re still working on that original timeline.”

That timeline faces heavy review now. South Australia Police Commissioner Grant Stevens said Wednesday that two family members have stopped cooperating. “Gus went missing on the 27th of September and we still don’t have clarity as to exactly where Gus might be,” Stevens told reporters. “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.”

He confirmed the pair had withdrawn support recently. “We are still getting significant assistance from Gus’ mum and dad,” Stevens added.

Separately, one grandparent faces unrelated firearms charges. Josie Murray, who lives at the Oak Park homestead, got hit with them after a police search. She’s due in Peterborough Magistrates Court on May 6.

Stevens said he lacked details on the exact offenses. “It is my assumption that they relate to either storage, ammunition, registration licensing,” he noted. He explained police can enter properties with registered firearms or prohibition orders under the Firearms Act. Warrants cover other cases.

The remote station’s isolation complicates the case. Shearing season was underway when Gus disappeared. Family members have given varying accounts. Task Force Horizon keeps digging into leads across the outback property and beyond.

Officers have revisited the scene multiple times. Cadaver dogs and ground-penetrating radar aided earlier sweeps. Fresh photos from the latest search show teams in hard hats probing dark shafts and ripping up floorboards. Still, the boy remains missing.