Police are offering a $50,000 reward in an unsolved Auckland murder case.

Brett Fraser was killed on the night of October 21st at a warehouse property he shared with a flatmate in Glen Eden.

Police believe the incident was motivated by a cannabis robbery run by Fraser's flatmate.

Fraser suffered a blunt force injury, and since then police have spoken to a large number of people.

Detective Inspector Bruce Scott says while Fraser was living at a house where drugs were being grown, no-one deserves to die on a cold warehouse floor at the hands of another person.