Two brothers who were attacked in their North Canterbury driveway - one fatally - were on the methadone programme, a family friend says.
Tony Lochhead died and brother Peter suffered moderate injuries in the incident in White St, Rangiora.
Peter Lochhead was discharged from hospital yesterday.
The friend who spoke about the brothers said they had moved to Rangiora from nearby Waikuku Beach, where they grew up.
Detective Inspector David Long said a silver Subaru station wagon seen being driven erratically soon after the murder might hold the key to solving the case.
It was found dumped at the Ohoka off-ramp.
"We are following a number of lines of inquiry but there are no firm suspects at this stage."
Meanwhile, a Facebook page belonging to Huntly murder victim Edward Tahakura depicted images of guns and drugs.
Tahakura, whose body was found at Otaki Beach on Thursday, posed topless with handguns in pictures on the social networking page and boasted of looking after marijuana crops.
A 24-year-old man has been charged with his murder.