Waikato police say the reason Paeroa businessman Jordan Voudouris was shot to death four weeks ago is still a mystery.
Mr Voudouris, 55, a pizza restaurant owner, was found dead behind his shop in the early hours of 18 June.
Police say Mr Voudouris died after being shot, but are refusing to say which part of his body was wounded.
Detective Senior Sergeant Mike Whitehead says it appears Mr Voudouris was behind his shop when he was shot and was able to to get to a gate, a distance of about 30 metres, before collapsing.
It is not known just what the victim was doing outside, says Detective Senior Sergeant Whitehead, but he is estimated to have died sometime between 1.30 and 4.30 in the morning.
"We've had a report from one neighbour of hearing what they thought was a shot and we've also got reports of raised voices at the rear of Mr Voudouris's premises," Detective Senior Sergeant Whitehead says.
He is not saying what type of firearm police believe was used.
Asked whether there had been a robbery, Detective Senior Sergeant Whitehead said nothing was missing from Mr Voudouris's property or his person.
Police believed the key to solving the case still lies in Paeroa, and that possibly a person is holding back significant information.
Police say a close look into Mr Voudouris's life has revealed nothing of concern.