Police believe a 22-year-old security guard died from head injuries after being assaulted on his first night at work at a West Auckland construction site.
Charanpreet Dhaliwal's body was found slumped over a slab of concrete just after 3am on Friday last week at a Fulton Hogan construction site in Henderson near the Northwestern Motorway.
Early this week, police said they did not believe Mr Dhaliwal was murdered, but had not ruled out foul play completely. Last night, they upgraded their investigation into his death to a homicide.
They are still looking for several men believed to have been "misbehaving" in the area.
A source told the Weekend Herald the men were not thought to be connected to Mr Dhaliwal's death but might have seen something that would help the investigation.
