Canterbury police have named the man found in a burnt-out car as 28-year-old Christchurch man, Shane Malcolm Bell.
A post mortem has now been conducted on the man's body, which was found north of Christchurch on Sunday.
Four-wheel-driving enthusiasts discovered the body at about noon on Sunday in the driver's seat of the burnt-out 1989 silver Subaru station wagon at the southern end of Dunlops Road, near Loburn.
The death is being treated as suspicious.
Detective Senior Sergeant Brian Archer said an extensive scene examination and interviews with witnesses were done yesterday.
He said the area was commonly used by recreational hunters and that the discovery was "certainly unpleasant".
"They were four-wheel-drive enthusiasts who had been driving around the riverbed. They came across the car and were curious, and had a look at it," he said.
The fire was already out. Only the front registration plate was on the vehicle.
He said the body was "extensively" damaged by the fire, the cause of which was yet to be determined.
The last reported sighting of Bell was at his home in the Christchurch suburb of Dallington on the morning of Thursday morning November 29.
Bell's family and partner have been spoken to by Police.
"At this stage the enquiry remains a suspicious death investigation," said Detective Senior Sergeant Brian Archer. "We are trying to put together a picture of the deceased's movements in the days leading up to his death.
"A key component to this investigation is determining when the car was burnt out. We now believe this was prior to Thursday evening. A member of the public who was in the area has come forward to Police and indicated they had seen the burnt out shell of the car at around 4 to 5pm on Thursday."
Police have now discounted bullet holes found in the side of the car as being related to the fire or the death.
"A group of recreational shooters has come forward and told Police they were in the vicinity on Friday evening. They have indicated that the car was already burnt out at that time, and that they fired shots at the vehicle using a rifle."
Archer said several people had come forward with information after an appeal for sightings of the vehicle between Thursday afternoon and Sunday.
"It is possible that people using the four-wheel-drive tracks in the area may have seen the burnt-out car over the past few days and we urge them to contact police as soon as possible," Archer said.
The area was often used by four-wheel-drive and off-road drivers, he said.
A Loburn resident, who asked not to be named, said young people often used the riverbed for wheelies and cars were often dumped there and burnt. However, she said there had never been "anything like this".
"It's quite unnerving." Anyone with information should phone the police on 03 363 7400 or the Crimestoppers line on 0800 555 111.