Convicted double killer Mark Lundy has asked New Zealand's highest court to look at his case as he attempts to overturn his convictions for murdering his wife and daughter.
The Supreme Court today confirmed Lundy's legal team has filed for leave to appeal after the Court of Appeal turned away a challenge earlier this year.
A substantive hearing will only be heard if the Supreme Court grants Lundy's leave application.
After the failed Court of Appeal bid, Jonathan Eaton, QC, told the Herald it was inevitable he would ask the Supreme Court to review the case.
"In the end we have been left sure of Mr Lundy's guilt," Justices Helen Winkelmann, Mark Cooper and Raynor Asher said in their Court of Appeal decision.
The latest legal steps are another piece in the long-running saga - which includes two trials - since Christine and Amber Lundy were found brutally killed in their Palmerston North home in 2000.
The pair had been hacked to death, likely with an axe or tomahawk, but the murder weapon was never found.
On the night of their murders Lundy had checked into a motel in Petone where he called an escort about 11.30pm.
It was fiercely contested during Lundy's first trial whether it was physically possible for him to have travelled from Wellington to Palmerston North in time to commit the murders.
A jury thought it was and convicted him of both killings in 2002.
Lundy's first appeal attempt resulted in the court increasing the non-parole period of his life sentence to 20 years.
But his conviction was quashed by the Privy Council in 2013.
The United Kingdom judicial body ruled there were problems with the analysis of the brain tissue found on Lundy's shirt, as well as with the time of death.
The Crown argued Christine Lundy's brain tissue was found on the polo shirt Lundy wore on the night of the murders. Tiny spots consistent with dried blood were also found on the shirt which were found to contain Amber's DNA.
However, after a retrial in 2015 in the High Court at Wellington, Lundy was again convicted by a jury of both murders.
A key change in the Crown case between the two trials was it abandoned the position of an early evening time of death.
Lundy's current appeal contends the 2015 jury should never have heard the mRNA evidence, arguing the analysis was too new and unproven to be relied upon.
Similar to DNA evidence, mRNA evidence was used to rule if the tissue on Lundy's shirt had a human or non-human source.
The Court of Appeal agreed the mRNA tracing was inadmissible but did not accept it had prevented the defence from arguing the tissue found its way onto the shirt through food.
"Mr Lundy has long argued that for whatever reason his case has become the testing grounds for novel science," Eaton said after the appeal court's decision in October.
"It was the novel use of the IHC [Immunohistochemistry] that lead to a successful appeal against conviction before the Privy Council back in 2013 and it was novel use of the mRNA evidence that was the primary focus of the 2017 appeal.
"The Court of Appeal has found that the mRNA evidence was wrongly admitted at his 2015 retrial."