A man jailed for a minimum of 17 years for the execution-style killing of a New Plymouth woman appealed his conviction and sentence on Wednesday.

Duncan Frost, 49, was found guilty of murdering 55-year-old Angela Deane by stabbing and slitting her throat as she cooked dinner in February 2007.

He was jailed for life with a minimum non-parole period of 17 years.

In the Court of Appeal in Wellington today, Frost’s lawyer Susan Hughes said he had a personality disorder which caused antisocial and narcissistic tendencies.

A psychiatrist gave evidence during the trial but some of the testimony was deemed inadmissible, weakening Frost’s case.

Justice Bruce Robertson pointed out that, through some legal manoeuvring on the part of Frost’s defence team, all the psychiatrist’s evidence came out in open court anyway.

Justices John Wild and Robertson said this was irrelevant as the psychiatrist’s opinion had not been challenged before the jury.

“It didn’t affect the bottom line at all,” Justice Wild said.

Fellow defence lawyer Kelly Marriner then argued against the length of sentence.

Frost had admitted the killing but claimed he was provoked as Deane had been involved with the drug P and had been killed as part of Frost’s crusade against methamphetamine.

Frost told police he stabbed Deane through the heart after slitting her throat did not finish her fast enough.

Marriner suggested this was evidence of his lack of callousness as he had “put her out of her misery”.

Justice Wild said another interpretation could be that it was, as sentencing judge Justice Paul Heath described it, “a cold blooded execution”.

Crown prosecutor Annabel Markham said Frost had admitted deriving pleasure from the killing and reminded the court he had a history of violent offending.

The Appeal Court judges reserved their decision.