The body of a man was pulled from the Heathcote River in the Christchurch suburb of Opawa on Friday.
A member of the public walking alongside the river in Aynsley Terrace saw the body and alerted police just before midday.
Police spent almost an hour photographing the scene, with some photos being taken from a cherry-picker, which was also used to help remove the body from the water.
Detectives also searched a park beside the river.
Louisson Place and part of Aynsley Terrace next to the Heathcote River were cordoned off for most of Friday afternoon.
Detective Senior Sergeant John Rae said the body was believed to be that of a 44-year-old local man, whose family officers have spoken to.
A post mortem was carried out on Friday evening and the cause of death has been established.
Police say there were no suspicious circumstances and they are not looking for anyone else in relation to the death. The matter has been referred to the coroner.