Mr Kohu led two police officers on a car chase towards Raetihi, "driving in a highly dangerous manner".
The chase ended when one of the policemen used his patrol car to push Mr Kohu's car off the road and into a wire fence.
The position of the car against the fence made it difficult for Mr Kohu to get out of the driver's side. As he was still in the car, the first officer approached him with a Taser.
Mr Kohu pulled out a sawn-off, semi-automatic .22 rifle and "fired directly" at the officer. Both police ran for cover as Mr Kohu climbed out the car window and continued firing at them. Justice Ellis said he fired five shots in total.
The officers fled to a nearby house and Mr Kohu, with co-offender Hereina Paul, stole the police car and left the scene. However, the vehicle got stuck, and the pair called a friend to collect them. They then went to Bushell's house in Tangiwai.
At 9.14pm, armed offenders squad members were stopping cars to check for the missing pair, and an officer noticed movement under a blanket in Bushell's car.
Paul was found in the back seat while Mr Kohu was discovered lying across the rear footwell with a gun believed to be the one used against the policemen.
The gun was "loaded with live rounds of ammunition", Justice Ellis said.
Bushell told police driving Mr Kohu made him feel "pretty bloody anxious" but said "I just wanted to get rid of him and get back to my family and work". Mr Kohu died in Whanganui Prison last year.
Paul pleaded guilty to being an accessory after the fact to attempted murder, as well as helping Mr Kohu avoid arrest and unlawfully taking a motor vehicle. She is yet to be sentenced.
"You probably felt like you didn't have much in the way of options that day. You nonetheless did choose to do what you did," Justice Ellis told Bushell.
She sentenced him to 250 hours of community work and nine months of supervision.