Gus Lamont disappeared from his family’s outback home in South Australia more than four months ago, prompting what police described as one of the largest and most intensive searches in the state’s history.
Police confirmed on Thursday that the case has now been formally declared a major crime.
The officer in charge of major crime, Detective Superintendent Darren Fielke, said the scale of the search had been unprecedented.
Mounted police, divers, defence and emergency services personnel, drones and Aboriginal trackers searched the 60,000-hectare Oak Park Station near Yunta, about 300 kilometres inland from Adelaide.
Until now, police have said there was no evidence of foul play, but they have also stressed that no line of inquiry has been ruled out.
Fielke said investigators are examining multiple possibilities, including whether Gus wandered away, was abducted, or whether someone known to him may have been involved.
