The man found guilty of murdering road worker George Taiaroa near Rotorua five years ago has lost his appeal against his conviction and sentence.

Taiaroa, 65, was shot dead as he operated a stop-go sign at roadworks on Tram Rd, Atiamuri, in 2013. The two men had a minor incident a week earlier.

Quinton Winders took his case to the Court of Appeal in March, arguing certain parts of evidence shouldn't have been used in the High Court jury trial.

His lawyer Philip Morgan QC said evidence that Winders had a propensity to overreact to "innocuous" events by shooting at or near people, should not have been heard in the High Court.

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But in a just-released decision from the Court of Appeal, that argument has been dismissed.

The decision noted there were three witnesses to the previous behaviour, who between them gave evidence about four separate incidents of shooting at or near people.

The Court said a pre-trial ruling allowed the evidence, and the evidence given in trial was consistent with what had been expected.

Morgan had also argued statements from Winders following his April 2013 arrest shouldn't have been used, because his detention at the time was unlawful.

But the Court of Appeal noted that during the police interview, Winders didn't seem reluctant to speak to police, and confirmed "on a number of occasions" that he was happy to help with their inquiries.

In the appeal against his sentence, Morgan questions the High Court's findings that the murder involved calculated planning by Winders.

The Court of Appeal upheld that part of the High Court decision as well, ruling that the planning "need not be competent or significant, but must be present to a heightened degree".

"The planning included Winders determining where Mr Taiaroa would be working that day," the decision said.

"After collecting his vehicle from the panel beater at 9.30am, Mr Winders returned home to collect his rifle before driving over 200km from Stratford via Taumarunui to Atiamuri to carry out the murder at approximately 3.15pm.

"The means of carrying out the murder at that location were carefully planned, as was the intended escape route and the various means by which Mr Winders would minimise the risk of detection."

The appeals against conviction and sentence were all dismissed.

Winders was sentenced to life imprisonment with a minimum non-parole period of 17 years in December 2016, after a jury found him guilty of killing Taiaroa.