Police now say the woman possibly did hear the shot that killed David John Robinson, who was just 25 at the time.
A homeless, transient petty thief, he had been shot between the eyes, execution-style with a single shot from a .22 calibre gun.
His body was found on the beach at Bold Head, near Ross, on December 28 1998 though police believe he was killed about 10 days earlier.
To this day, police have failed to find the murder weapon, murder scene, his bag — or the murderer.
"I heard a single gunshot. It was very, very loud, the birds flew away. Then dead silence. I dropped the hose and ran inside, I got quite a fright. I went to the front window and had a look around, but I couldn't see anything at all."
A new detective is currently looking at the cold case, and he said he could not rule out that the witness had actually heard the fatal shot.
"It fits in with the location, the tidal information and the entomology (insect) analysis," Detective Sergeant Brent Lyford said.
The woman said that when Mr Robinson's body was first found, police did not seem interested in her account.
"They seemed to think he was shot on the beach," she said today.
"I'm sure it was the shot. The date and everything else fitted."
After a recent newspaper story, several others have contacted police. Det Sgt Lyford said the information still had to be assessed against information already held on the file but some avenues of investigation were identified.
There is talk of a new suspect after a re-examination of the voluminous case file.
Det Sgt Lyford said there had been no further interviews at this point, and further inquiries and analysis would be needed first.
"I have seen nothing firm to date that leans me toward believing a gang was responsible for David's death," Det Sgt Lyford said.
"I can't say that a local was or wasn't responsible for David's death. I think it would be fair to say that whoever is responsible must have some connection to the area due to how remote it is. A lot of this detail will be further looked into again in the near future."
Police now believe that after Mr Robinson was shot his body was thrown into a river — probably the Kakapotahi, at the bridge just before it merges with the Waitaha River. It then washed out to sea, around Bold Head on a northerly flow, and was washed up on to the beach.
The pathologist also found a severe fracture in his skull, which possibly could have been incurred if his head had hit a rock when he was thrown off a bridge and into a river.
Mr Robinson's mother Joan now lives in Hokitika and wants to see justice for her son.
"That's how his ending was. Kneeling on the ground, begging for his life. And these big brave people shot him… I don't know how they could live with their conscience. I really don't," she said.
