The scene examination around a body found on a Nelson boat has spread to two other boats in the marina.
A man's body was found in the back of a white boat at Nelson Haven near busy State Highway 6 on Thursday, and police are treating the circumstances as suspicious.
Detective Inspector Paul Borrell says it appears the man had been seriously assaulted.
Police believe they know who the man is but are yet to formally identify him, so won't be releasing his name.
They've described him as European and didn't own the boat he was found on. He was last seen alive on Wednesday afternoon.
At a news conference, Det Insp Paul Borrell said while the death is suspicious, they're not sure if it is a homicide.
"We are working to establish how the victim received his injuries and are hopeful the post-mortem will provide some clarity." The post-mortem is expected to be completed on Saturday.
Forensic scientists and specialist police staff are helping with the scene examination, which now includes three boats. They're expected to be there for a number of days.
The boat has since been covered by a tent as the scene examination goes on.
Police want to hear from anyone frequently in the area, including commuters and those who use the skate park opposite where the boat is moored - particularly on Wednesday night and Thursday morning.
Anyone with information should call police on (03) 546 3895 or anonymously via Crimestoppers on 0800 555 111.