A combination of alcohol and silly antics inside the car may have caused last weekend's horror crash near Woodend.
The crash initially appeared to be an overtaking manoeuvre gone wrong.
The car crossed the centre line into the path of a southbound Northern Star bus about 11.20am on Saturday.
However The Star has learned that police are investigating whether one of the four passengers reached over and moved the steering wheel moments before the impact.
Empty beer bottles were also found in the vehicle.
The driver, Dean Jonathan Mcartney, 21, of Motukarara, and passengers Kodee Marie Rapana-Aldersley, 15, and Jethro Bronson Cooper, 16, of Leithfield, died at the scene.
Funerals were being held today in Rangiora for Kodee and Jethro, and in Nelson for Mr Mcartney.
The two surviving passengers - front seat passenger Worthy Redeemed, 37, and rear left-side passenger Rhys Durham, 16 - were yesterday both still in hospital.
The Star
understands that police started investigating the steering wheel being moved after interviewing Rhys and witnesses of the crash.Police are yet to interview Mr Redeemed, because he remains in a serious condition.
The movements of two of the passengers have also been revealed. Friends Rhys and Kodee were picked up from his Amberley home not long before the crash.
The car then travelled to the Shell petrol station at Waikuku, where Rhys paid for petrol about 11.15am.
They then drove north until the point where they crashed.
Police would yesterday not be drawn on the investigation into the steering wheel being moved.
However Detective Sergeant Rex Barnett confirmed that the behaviour of the occupants of the vehicle was being looked at. "We are trying to establish the driving and the behaviour of the occupants... particularly between Amberley and the crash scene from 11am onwards," he said.
"Clearly the car was on the wrong side of the road. The question is how or why was it there? There are various possibilities."
He said police were waiting until Mr Redeemed was in a condition to speak to them.
Detective Sergeant Barnett said there was some suggestion alcohol was involved. Bottles of beer had been consumed, but whether that contributed to the crash was yet to be determined, he said.
The Nelson Mail reported this week that Mr Mcartney recently moved down from Nelson to turn his life around. He had reportedly left a criminal background behind and was working for Pathway Trust, a charitable group that provides employment, accommodation and social-work support.
Detective Sergeant Barnett said police were still hoping to speak to more witnesses of the crash.
Some drivers may have left the scene before police arrived, he said. Anyone who witnessed the crash, or saw the gold Mitsubishi Mirage before the crash is asked to contact Rangiora police on 313 6166.
The driver of the bus is back at work on limited duties after receiving counselling, said Christchurch Bus Services director Clive Peters.
The driver did not wish to speak to media.