A minor road accident has been singled out as the "inexplicable" reason why road worker George Taiaroa was shot dead.
The Crown opened its case against Quinton Winders in the High Court at Rotorua on Monday, claiming the accident - which happened a week before the killing - was the catalyst for a crime "which shocked the nation".
Crown lawyer Amanda Gordon says when the accident occurred, on March 12, 2013, Mr Taiaroa was manning a stop-go sign in Atiamuri.
She says Winders had been with his father, Max Winders, who "overshot" the sign and ended up having to reverse his Land Rover Defender.
He had a stock trailer connected to a truck, and that hit another car - a Ford Telstar - causing minor damage.
At the time, Mr Taiaroa had the stop-go sign in a road cone. He was sitting on the back of his ute, operating the sign.
Ms Gordon says Winders was overheard saying after this incident, "If the stop-go guy had been doing his job properly, this accident would not have occurred."
The Crown alleges this was the catalyst for the killing - that Winders was so incensed about the incident, he returned a week later and shot Taiaroa.
The damage bill for the Ford Telstar was $989.58.
More than 130 witnesses will be called during the four-week trial.