Police searching for a missing four-year-old boy in Australia say they have not given up hope, even as the huge operation to find him has been scaled back after nearly a week of fruitless searching.August 'Gus' Lamont vanished from his grandparents' remote Outback homestead, about 25 miles south of Yunta, north-east of Adelaide, on Saturday afternoon.While the chances of survival are slim after six freezing nights, officers admit Gus may still be alive in one of the region's countless unmarked wells or mine shafts.Despite this, conspiracy theories have flooded social media, with some users suggesting the four-year-old was abducted. Police say there is no evidence to support this.Locals and police believe the most likely explanation is that Gus simply wandered off from Oak Park homestead and slipped into an unseen shaft. The boy was last spotted by his grandmother at around 5pm on Saturday. He had been playing on a mound of dirt near the front yard of the property, which is reached by travelling through six gates across rough country. When she went back out to call him in just 30 minutes later, he was gone. A frantic search by family and neighbours quickly escalated into one of the biggest operations in South Australia's history, with hundreds of volunteers, police officers, trackers and even Australian Defence Force personnel scouring the region.Only one possible clue has been found - a single footprint, about 500 metres from the house. Yorke Mid North superintendent Mark Syrus admitted that was unusual. With no clear sign of him after days of searching, theories continue to swirl online. A picture of August 'Gus' Lamont. He went missing from his grandparents' remote homestead, nearly 25 miles south of Yunta, north of Adelaide on Saturday afternoon