An intensive search by family, police, friends and helpful strangers wound down on Monday, with police warning he might never be found, but his family continued looking.
About midday, Lucas was found 400m upstream of his grandparents' property by a member of the public on a surf ski, a discovery that was a relief for police and searchers.
"I'm sure this will bring some sort of closure for the family of Lucas," Gisborne area commander Inspector Sam Aberahama said this afternoon.
"This is an incredibly distressing time and our thoughts are with them and their extended family as they grieve for their little boy."
He was confident his staff had done everything possible to find Lucas, he told Radio New Zealand.
The search had centred on the Waimata River near his grandparents' house, and while the effect of the tides was accounted for, the focus had been downstream, not upstream.
Police divers scoured the area after his bike was found on a path leading to a river jetty. A chip packet was also recovered from the river, believed to be similar to one given to him by his grandmother shortly before he disappeared on Tuesday afternoon last week.
"While indicators pointed towards the river, it was important to keep an open mind I believe, and as such we carried out a meticulous search of the land areas and of the water," Mr Aberahama said.
Lucas went missing as his grandmother unloaded groceries then answered a phone call in her suburban Kaiti home. He was described by his parents as curious, and had been known to wander off, but never for long.
"He is a very confident child, he is not fearful of leaving my side. He is a very, very friendly child to the point he could quite easily go off with a stranger to have a sleep over at someone's place," Mrs Ward had said.
Hundreds of volunteers and thousands of wellwishers had hoped for his return.
The timber product company where his grandfather works put a helicopter in the air, and staff combed city beaches in boats, looking for clues.
Police today said they were keeping an open mind on how Lucas died. A post mortem examination will be conducted and the case referred to the coroner.
