The Court of Appeal has upheld Mark Lundy's convictions for the murders of his wife Christine and daughter Amber.

Photo: RNZ / Sharon Lundy

Lundy had twice been found guilty of murdering his wife and daughter and went to the Court of Appeal in October last year in an effort to have his 2015 convictions overturned.

The bodies of Christine Lundy, 38, and Amber, 7, were found by Mrs Lundy's brother in their Palmerston North home on 30 August 2000. Both had been bludgeoned to death.

Lundy was first convicted in 2002 but the convictions were set aside on appeal to the Privy Council.

He was tried again in 2015 and it was those convictions that were under appeal.

All but one of the grounds for appeal were rejected in a decision released today.

Lundy had argued there were significant omissions from the judge's summing up in the 2015 retrial and that the Crown's case in the retrial had changed compared with his first trial.

At the first trial the Crown suggested he had driven at break-neck speed from Wellington to Palmerston North, killed his family and driven back to Wellington.

However, at the retrial in 2015 it said the deaths had occurred early on the day the bodies were found.

During the appeal Lundy's lawyers said they had only been made aware of that change in the Crown's case shortly before the retrial began, but the Crown lawyer said the defence had known about it since 2014.

The defence also claimed the jury may have indulged in 'demeanour reasoning' based around claims that funeral footage showed Lundy 'feigning' grief.

Lastly the defence said the jury was 'drowning in a sea of science' and should not have had the mRNA evidence before it.

Messenger RNA, or mRNA, is similar to DNA but allows a scientist to pinpoint which part of the body a particular piece of tissue is from.

The Court decided that the mRNA evidence was inadmissible.

In its decision the court said a number of specific issues were raised for Lundy but, having considered them, it had determined that none, on their own or collectively, undermined the strength of the Crown case.

"The Court is sure of the guilt of Mr Lundy notwithstanding the rejection of the mRNA evidence," the decision read. "It is also satisfied the trial was fair."

Massey University's pro vice chancellor professor Chris Gallavin said he was surprised by the decision.

"Effectively the defence won every aspect of their legal argument.

"They were arguing that the novel scientific evidence that resulted in a positive affirmation of the material being on Lundy's shirt was more likely to be brain or spinal matter and the defence won in their argument saying that not ought to have been admissible."

"What was really interesting was the Court of Appeal still, nonetheless, said that wasn't really of sufficient significance to change the conclusion of the case and part of me finds that quite remarkable."

In the retrial the Crown introduced new evidence from a scientist in the Netherlands who determined matter on Lundy's shirt was from a human brain or spine.

However, the defence team rejected that saying the science was 'experimental' and not sufficiently developed for forensic use.

That part of the defence's appeal was accepted by the Court, but overall it said the Crown's case against Lundy was still strong without that evidence.

"That wasn't pleaded by the Crown in their initial submissions... in the eleventh hour that raised its head. So they won this case on an issue that - at least going into the appeal - they didn't seem to have any intention of arguing whatsoever."

Mark Lundy's brother Craig said the past year had been hard.

"Painful, just sitting, waiting, a year is a very long time, it's just been a long couple of decades really.

"It is what it is, I can't really do anything about it, I just got to protect me and my own," he said.

But he added the right decision has been made by the Court.

"Well it's taken a year, but we've got a decision and that's one that I think is correct and now we'll see what he does from here," he said.

Lundy's lawyer Jonathan Eaton QC said Lundy was disappointed at the outcome of the appeal.

"That decision raises important issues and is inevitably one that Mr Lundy will ask the Supreme Court to review," he said.

Timeline of the Lundy case