Police have confirmed a Nelson man suffered a “very violent attack” which led to his death.

Detective Senior Sergeant Craig Johnston said a post mortem on the body of John Murray ‘Muzza’ Morton was completed in Christchurch yesterday and confirmed they will now be treating his death as a homicide.

"The number and nature of Mr Morton's injuries suggest a very violent attack and the investigation team is determined to piece together exactly what happened,” he says.

Morton, 55, died overnight on Wednesday and lived in one of three boats that often frequented the Nelson Haven area.

However, his body was not found in his own boat when he was discovered on Thursday morning.

Extra resources are being brought in from other police districts and the Nelson team will be joined by further investigators on Monday.

Police are now interested in photos that members of the public may have taken in the area recently.

"Police are keen to hear from anyone that uses the reserve area or may have recently taken photographs of the area of QEII Drive opposite the skate park - particularly the boats that are moored there, as this will help us with our reconstruction of the scene and recent activity there."    

"I believe people in the Nelson community may hold the keys to unlock this mystery and I urge anyone with information about what happened to Mr Morton to come forward and help us hold to account the person or persons responsible for this senseless crime."   

Although police are still working out how Morton died, they didn’t believe anyone else was in danger.

“This is however a good time to remind everyone to think about their personal security at all times, and to keep homes and vehicles locked and report any suspicious incidents as they occur.

"Nelson is a safe place to live and with the assistance of everyone in the community we can keep it that way."

Anyone with information that may be relevant to the investigation into Morton's death is asked to contact Nelson Police on 03 546 3840 or alternatively it can also be provided anonymously via Crimestoppers on 0800 555 111.