Searchers spent almost five days looking for Luke Shambrook. Credit:Joe Armao State Emergency Services personnel, the Victoria Police canine unit and mounted police were among those to lead the search in the cold conditions at first light. Volunteers also began arriving early to search the Lake Eildon holiday spot, as they have done over the previous four days and nights. Sergeant Greg Paul addressed 60 volunteers shortly before 10am, instructing them to re-search nearby areas in case Luke was "on the move". He asked them to pay close attention to culverts and tree hollows, and to call out every few minutes, then stop and listen for a response.

Luke Shambrook, far left, with his family. "We're racing against the clock. We're racing against the weather," Sergeant Paul said. "It's a life and death struggle. We want to get him found today." The Monday afternoon discovery of a black beanie confirmed to be Luke's has buoyed the spirits of those searching. Candlebark Campground in Lake Eildon National Park. Credit:Penny Stephens It was found next to the steep Auciferous Spur Track, between the Koala and Orchid rivers, west of Devil Cove, indicating that Luke at some point walked away from the water.

The terrain near there is craggy with thick forest, and while the underbrush has recently been dusty and dry, on Tuesday morning it turned to mud. Line searches are targeting that area. Police want to ensure it is "100 per cent clear" inside a two-kilometre radius before expanding the search area. "It's an indication of where he's been, so it is significant," Acting Senior Sergeant Andrew Walker said. "However we don't know when Luke had dropped that beanie … It's quite possible he dropped it on the Friday morning." He added that the search was "no more urgent" than it was when Luke went missing, "but with every day that passes everyone is concerned for Luke".

The family, Acting Senior Sergeant Walker said, were "very concerned, as we are", but there has been no discussion of scaling back the resources for the operation. "We're treating this as a search and rescue operation," he said. "We'll be back tomorrow in the hope that we'll find Luke alive." Volunteers have been steadily arriving at the park to help in the search. Scott Patrick woke at 6am, took the day off work and drove to the search area from Broadford with his six-year-old son Nayte. His said his family had camped in the area for decades, and he had a four-wheel-drive with GPS and satellite phone.

Mr Patrick said he had friends with autistic children, but would want the same help if it were his son or daughter that was missing. "This could be anyone's child," he said. "I don't know if we can do much, but we've gotta try." Victoria Police confirmed that the boy had a "high pain threshold", and was described by his family as "resilient". They also said that he enjoyed hiding, so searchers were looking in any and all obscured spots. Police said that Luke's occupational therapist had been consulted, who suspected that he would not have wandered far from the campground. The boy spent his fourth night in the wilderness on Monday, when the temperature dropped to 8.8 degrees. Up to 5 millimetres of rain is expected to fall around Lake Eildon on Tuesday. Meanwhile, the daytime temperature is not expected to rise above 13 degrees.

Luke's family remain at the campground in the Lake Eildon National Park and have thanked all those who are helping in the search. "We continue to express our thanks to all involved in searching for Luke," the family said in a statement. "Everyone's ongoing involvement and support is overwhelming and still greatly needed." With Robyn Grace