By Amelia Romanos
Jurors in Mark Lundy's 2002 double-murder trial were misled about the reliability of the method used to establish when the victims died, the Privy Council has been told.
Lundy, who was found guilty of bludgeoning his wife Christine and their seven-year-old daughter Amber to death in their Palmerston North home in 2000, is appealing his conviction at the London court.
On the second day of the hearing on Tuesday (local time), his lawyers focused on the time the victims died, which Palmerston North pathologist James Pang determined, based on their stomach contents, was between 7pm and 7:15pm.
David Hislop, QC, told the court Dr Pang's tests had been internationally rejected and experts said the idea that time of death could be measured within minutes based on the gastric contents was "scientific nonsense".
Time of death was pivotal to the case and the jury was deprived of evidence that would have contradicted Dr Pang's findings, Mr Hislop said.
Cellphone records placed Lundy in Petone at 5:43pm and then again at 8:28pm on August 29. The prosecution's case was that he drove from Petone to Palmerston North, committed the murders, then returned to Petone - a journey of 150km - within three hours.
"All the defence really had to do was stretch [the time of death] beyond 7:15pm, then the travel to Wellington becomes impossible and he has an alibi," Mr Hislop said.
New Zealand chief justice Dame Sian Elias, who is among five justices hearing the appeal, summed up the argument, saying to Mr Hislop: "Your case really is that because the window of opportunity the Crown's relying on is so small... that the jury should have been told that it was impossible to estimate [time] of death from gastric contents with such precision."
Mr Hislop also contested evidence that Lundy had tampered with a computer to make it appear that files were changed hours after the deaths.
The crown on Tuesday had its first opportunity to respond at the appeal.
Deputy Solicitor-General Cameron Mander said there was no fresh evidence, and Lundy's team was relitigating what was presented at trial.
He also challenged accusations of "bad science" regarding a stain on Lundy's clothes, which the prosecution says was Christine Lundy's brain tissue.
In 2002, Lundy was convicted and jailed for a minimum period of 17 years. He appealed his conviction in the same year but the Court of Appeal increased his minimum term to 20 years.
The Privy Council hearing is expected to conclude on Wednesday.
There was some discussion from the panel regarding the conflicting views of experts, and the possibility of the case being remitted back to New Zealand's Court of Appeal for more evidence to be heard.