He went willingly when he was picked up from his home by people driving either a two-tone silver/grey Nissan Terrano or Toyota Surf, Detective Senior Sergeant Kim Libby said.
Mr Libby said one option was that the dead man was involved in drugs and he may have been killed when a deal turned sour.
"That is definitely the angle we are looking at. But we have got to keep our options open.
"He is an associate of a gang and it is all inter-linked with that sort of business - speed and methamphetamine."
Mr Libby said they were still looking for sightings of the car which was in the area of the forest in the early hours of October 18.
"We haven't identified the people who picked him up and they were the last people that were with him."
He said it was not known if the fatal stab wound was intended to kill him or if it was delivered in a fight.
- NZPA