Sergeant Ed Baker, of Dunedin police, said Donald James Caley was found at the changing rooms next to Guthrie Pavilion at Bayfield Park yesterday morning.
When ambulance staff arrived there were ''signs of life'', but Mr Caley died soon afterwards, Sgt Baker said.
Delta drainage foreman Evan Woodrow said his workers had been running new power cables between substations at the park, which is near Andersons Bay inlet. A Delta worker arrived at the park yesterday morning and telephoned emergency services after he saw Mr Caley lying unconscious on a bench outside the changing rooms.
The man had a wallet, a bag and bicycle helmet and had appeared to be dead, Mr Woodrow said.
Ambulance staff told him the man was diabetic and were in disbelief that a member of the public had not called emergency services earlier, he said.
A man approached the Delta crew yesterday morning and told them he had seen the man lying there on Sunday, Mr Woodrow said.
''The joker told me that he [Mr Caley] didn't look well. Why didn't somebody do something yesterday? They could have walked over and if he couldn't talk, you would have rung an ambulance, wouldn't you?''
That man would not have been the only person to have seen the unwell man because the park was used regularly by many people, Mr Woodrow said.
''It's rude that people have walked past and left him there like that, especially last night with it being so cold. It shouldn't have happened. They should have called the police straight away. It's a free call. It is disgusting. Dunedin [people] are not looking after people who are sick. That's what it boils down to.''
Sgt Baker said if somebody was found unconscious, assistance should be sought immediately.
Mr Caley's death was not suspicious and he had a known condition, Sgt Baker said.
The earliest sighting of the man lying outside the changing rooms was on Sunday, between 9am and 10am, Sgt Baker said.
Police were interested to hear from anyone who had seen the man there before then.
Mr Caley had been missing for a couple of days, Sgt Baker said.
Senior Constable Rob Murray, of Dunedin, said Mr Caley worked as a labourer and was dropped near his home in South Dunedin on Friday evening, where he lived alone.
Dunedin City Council sport fields and facilities officer Harold Driver said the changing rooms at Bayfield Park were not booked at the weekend but the park was open to the public.
The park did not have a security patrol, he said.
Dunedin Track Club spokeswoman Netty Lastovicka said the Guthrie Pavilion had not been booked at the weekend.