A homicide investigation was launched on 28 December, 1998 after the body of then-25-year-old David John Robinson was found on a remote West Coast beach near Ross.
Detective Inspector Geoff Baber from the Tasman District police said Robinson was killed roughly 10 days before his body was discovered.
Baber said several of Robinson's possessions were found scattered across the beach, indicating he had likely been staying in the area before he died.
Police eventually scaled back their investigation after extensive enquiries, including interviewing several people in the community and conducting searches of nearby beach, bush, and river areas.
"The investigation has been periodically reviewed and police continue to make additional enquiries over the years.
"I want David's family and the community to know we will not give up. Police are determined to find out what happened in this small rural community, shortly before Christmas over 26 years ago."
Police would continue canvassing the Kakapotahi area in the coming weeks.
"David would have been 51 now, and while his murder was nearly three decades ago his family continue to grieve.
"We know people may not have wanted to previously tell us what they saw or heard, but the passing of time may have changed things for them, and they may see things differently now with regards to David and what happened to him.
"If you do know something, we encourage you to come forward and speak to us - it is not too late to provide David's family with answers."
People could email police via the cold case form on their website, or call 105 using the reference case number 231129/2221.
