Relatives and associates of a man who brutally killed at an Auckland house nearly six months ago are still withholding evidence about what happened, say police.

Damien Loder Allen, 33, was found dead with head injuries in the suburban Hillsborough property on September 24 and police at the time accused other occupants of refusing to cooperate in the investigation.

"Nothing has changed," said Detective Inspector Scott Beard today.

Police believe the house had been cleaned and his body had been moved before police arrived.

They said that vital information which could solve the mystery was being withheld.

Four people were in the house when police arrived and others had visited the house on the night.

Police were alerted to the slaying by a 111 call from the house.

Since then police said there had been a total lack of cooperation from those in the house or others who knew Mr Allen.