The man convicted of murdering his estranged wife in a frenzied knife attack has had his appeal dismissed.

Michael Preston who was sentenced to 19 years of imprisonment in December 2015 for murdering his wife Mei Fan failed to get the conviction over turned or the sentence reduced by the Court of Appeal.

The Wellington mother was stabbed 38 times in a frenzied attack in her Miramar home in November 2013. When her body was later found lying in a pool of blood on the laundry floor a knife was still in her neck.

The Court of Appeal judgement, released today, said Preston had not shown that a miscarriage of justice had occurred during the trial.

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It also found the life sentence imposed was in line with other cases, especially due to the high level of brutality, cruelty and callousness shown in the murder.

The basis of the appeal hung on statements from the Crown - many made in the closing argument - which Preston's lawyer Steve Gill said were not substantiated by the evidence earlier presented in the five-week trial which concluded in November 2015.

The trial contained graphic, bloody and highly emotional accounts at the High Court at Wellington.

One of the arguments queried was whether synthetic fibres found at the crime scene could have come from a witch's hat that was missing from Preston's house which had once been worn by him for Halloween. The Crown argued it had been used to conceal the murder weapon.

The hat had not been found at the house, but police testing on four similar hats found that two had black synthetic fibres made out of polypropylene, the same that found on Fan's body.

But Justice Helen Winkelmann felt the Crown had enough evidence to infer that the missing hat was the source of the fibres at the scene and rejected claims the prosecutor had invited impermissible speculation by the jury by speculating how the witch's hat could have been used in the attack because it was "not a critical part of the Crown case".

Preston's lawyer also took issue with the Crown counsel who said in his closing address that whoever did that hated Mei Fan. "This was very personal. The killer has the last say, saying there was no evidential basis for that."

However Justice Winkelmann said it was a "commonsense submission" due to the particular nature of Fan's attack.

"There were numerous knife wounds, suggesting 'overkill'. Moreover, the wound track of the final thrust was consistent with it being having been retracted a little before the final thrust. The killer also left the knife protruding from Fan's neck."

There was also an argument over whether there was any evidence to suggest how long the attack took, but Justice Winkelmann said that was up to the jury to determine based on detail presented.

"No expert would be in a better position than a jury to undertake the assessment," the judgement said.

It also found there was enough evidence to link Preston to a pair of bloody socks left at the scene, despite Gill arguing otherwise.

The appeal against what Gill said was an "excessive" sentence was also dismissed because Winkelmann said "no two cases were ever identical" and due to the nature of the killing which was brutal, cruel and callous to a very high level. The minimum penalty for a conviction of this nature is 17 years.