Two brothers who lived at the West Auckland home outside where Connor Morris was killed have gone into hiding amid fears of retaliation.
After receiving advice from police, the young men have not returned to their home since Morris was killed two weeks ago.
Detective Inspector Greg Cramer, heading Operation Venice, would not say whether police had identified any suspects in the investigation.
The brothers weren't under police protection, but police had advised "a number of people". It is understood the brothers have been assisting police with their inquiries.
Morris suffered a fatal head injury during a confrontation outside a party in the West Auckland suburb of Massey. He was held by his partner of six years, Millie Elder-Holmes, as he lay dying.