They decided to drive to the nearby Lake Ferry Hotel in King's car. King told police that during this time Mr Swinbank was driving.
At the hotel, King was served a jug of beer and Mr Swinbank a bowl of fries.
When the hotel closed at 7.30pm they drove to Martinborough, stopping at a friend's house in Te Maire Rd, about 8.30pm, where they drank beer from bottles King had in the car.
About 10.30pm they left the house and drove south on Kahutara Rd, South Wairarapa. About 5km from their friend's home, King lost control of the car, causing it to veer left off the road, at the end of a moderate right-hand bend.
Tyre friction marks showed the car veered to the right before going back to the left and leaving the road, hitting a sheep fence and pine branches before rolling into a power pole.
The car halted with the driver's side down in the ground and the roof up against the power pole, trapping the two teenagers.
Mr Swinbank died instantly on impact.
King was trapped in the driver's side with a serious facial fracture.
The crashed vehicle was discovered by a night-shift worker at 3am. The worker called emergency services.
"It is highly likely that the pair had crashed some four and a half hours before the crash was discovered," Ms Lawrence said.
Mr Swinbank was found belted into the passenger seat and was removed by fire staff trying to reach King.
King walked from the wreckage after fire staff undid his seatbelt. He was flown to Wellington Hospital, then to Hamilton Hospital, for specialist treatment.
Police scene analysis showed King was driving too fast for the corner, which caused him to lose control and crash, killing Mr Swinbank.
Judge Peter Hobbs convicted King and remanded him at large for sentencing on December 12.