Specialist police units have joined the search for 17-year-old William, who disappeared during a camping trip in dense terrain near Walhalla East, Victoria.
The Latrobe Valley teenager has not been seen or heard from for 72 hours after walking away from his campsite along the T2 Track near Stoney Creek Road on Friday.
William, who lives with autism, was wearing only shorts and work boots when he vanished. He also left his mobile phone at the campsite.
Victoria Police said they believed he may have become disorientated and lost his way in the surrounding terrain, adding that officers and his family were increasingly concerned for his safety.
A box of cereal and a packet of marshmallows found nearby on Monday have been identified by William’s mother as belonging to her son.
William had been camping with a 16-year-old friend after his mother dropped them off on Friday afternoon. He had never camped before and was unfamiliar with the area.
After the pair set up camp, William walked a short distance to collect a portable cooler. When he failed to return, his friend searched for him before running from the track to seek help.
The friend stopped the driver of a white ute, and police are now trying to trace the man and woman who assisted in the search. They were travelling along Stoney Creek Road between 7.30pm and 8.30pm in an older white four-wheel-drive with a tray and dark-coloured canopy.
Search crews have been working through dense terrain on foot and from the air, while a command post has been established in nearby Cowwarr to coordinate the operation.
Police have asked anyone who sees William to call triple zero. Anyone with information about his whereabouts is urged to contact Crime Stoppers.
