The case is now the subject of a new episode of Cold Case NZ, which will screen on TVNZ 1 at 8.30pm on Tuesday.
It wasn't until seven weeks after Christmas Day that a neighbour raised concerns about Hinkley who lived alone in a central city unit.
He was 1.84m tall and of solid build, and had a shaved head when he was last seen.
He was last seen wearing dark pants, a black T-shirt with a large white pattern on the front and a blue peaked cap with a dark blue logo on the front.
There have been no sightings of Hinkley reported to police since he went missing.
So what happened to him? Where is he? And who was involved in his disappearance? Watch Cold Case NZ on TVNZ 1 at 8.30pm or on TVNZ On Demand.