Dunedin police have named the victim as unemployed Oamaru man James Mathew Ellis.
Detective Senior Sergeant Kallum Croudis, of Dunedin, said the three in custody, aged 17, 25 and 47, were arrested on Saturday afternoon and have been jointly charged with the murder which was believed to have taken place in Warrington on Friday, following a gathering in Oamaru on Thursday night.
"We are still trying to locate witnesses who attended a gathering at an Oamaru address overnight on Thursday and early Friday morning.
"Mr Ellis and the three men facing charges appear to have been at the address."
Det Snr Sgt Croudis said a postmortem examination had revealed Mr Ellis died in what appeared to be "gruesome circumstances".
He received numerous blunt-force trauma injuries to his head, hands and arms. The head injuries proved to be fatal, Det Snr Sgt Croudis said.
The armed offenders squad was used to secure a house in Gilmerton St, Corstorphine, where the 47-year-old and 17-year-old were found and arrested on Saturday.
Both the Gilmerton St house and the home of the 25-year-old (also in Dunedin) were examined by ESR, along with the Oamaru house.
A green Mazda 626 and a white Mazda 626 saloon were also forensically examined as part of the investigation yesterday.
While police have recovered items which will be subject to analysis, they remained open-minded about Mr Ellis' injuries, Det Snr Sgt Croudis said.
He declined to talk about possible motives for the murder, or whether the men were known to police. However, he said all of the men involved knew of each other.
Mr Ellis was found dead by two people walking at the Blueskin Bay estuary behind Warrington Beach about 7.45am last Friday.
A homicide investigation was launched soon after, and a team of up to 40 police staff worked at Warrington over the past two days to carry out a scene examination and search.
The searches were completed yesterday.
The three arrested will appear in the Dunedin District Court tomorrow and police are expected to oppose bail for all but the 47-year-old.
Det Snr Sgt Croudis said bail would not be opposed because the man was believed to have "health issues".
"The result in bringing charges is a testament to the excellent collaboration and co-operation between police staff in Gore, Oamaru, Dunedin and Christchurch, as well as urgency around speaking to potential witnesses," Det Snr Sgt Croudis said.
Neighbours on Gilmerton St said the two arrested by the AOS were father and son.
One neighbour, who declined to be named, said the street had been plagued by frequent acts of violence.These were not related to the present homicide investigation, she said.
"The police are up and down here on a monthly basis," she said. "We don't need this."
