A post-mortem has confirmed the man who died in Ellerslie received injuries that were "violent, and consistent with foul play", police say.
A homicide investigation has been launched following the death of the 66-year-old man at a Celtic Crescent address.
Police were called to the man's home about 8pm Monday after he was found by a relative. He was pronounced dead at the scene.
"While Police had always been treating this investigation as a homicide due to our initial enquiries, the post-mortem has sadly confirmed the injuries received to the victim are violent, and consistent with foul play.
"Police now believe the victim died prior to Sunday afternoon as a result of the injuries sustained," Detective Inspector Beard said.
Beard said police were still appealing for information on the whereabouts of the man's wife.
She was last at the property over the weekend.
"We are very concerned for the safety and wellbeing of Mei Han Chong.
"Police have not yet located 67-year-old, nor the vehicle (a blue Kia Rio, registration NJN927) which belongs to the family.
"No piece of information is insignificant as we work to determine exactly what has occurred."
On Tuesday Beard said police had made inquiries to see if Chong has left New Zealand but at this stage that did not appear to be the case.
Asked if she was a suspect, he said they were keeping an open mind about what happened, and she could instead be a victim.
Beard told Checkpoint the car was driven by the deceased man from the North Shore just after 11pm Saturday 4 October. He could not say if his wife was in the car too.
A scene investigation continues and police would remain in the area in the coming days, he said.