Two teenage girls found a piece of human bone while walking along the beach at Fleetwood.
Although the bone was not initially thought to be human, tests showed it belonged to Brice Veevers, who was reported missing in September 2013.
Mr Veevers, from Nottingham, was staying at a Blackpool guest house when he vanished. He was 27 at the time.
Despite a police appeal at the time, he was not found – until the grim discovery last year.
Detectives say two girls – who they are keen to trace – handed the bone in to rangers at Rossall Point in either September or October last year.
Police only became aware of it in January and testing has since shown the bone belongs to Mr Veevers. His death is not being treated as suspicious.
Det Insp Jason Richardson, of Blackpool CID, said: “This is a very sad set of circumstances for the family and friends of Mr Veevers and my thoughts are very much with them at this time.
“We are keen to find out exactly whereabouts on the beach the bone was discovered so that we can begin a search of the area and we would urge the two girls who handed the bone in to the Rangers to come forward.
“I would also urge anyone else who uses the beach and may have found anything similar to get in touch with any information that could assist us with our search.”
Anybody with any information can contact police on 101.