Mark Lundy's final bid to overturn his convictions for murdering his wife and daughter has been unanimously declined by the Supreme Court.
One of his supporters said he was "not surprised" at the decision.
Lundy was previously convicted of killing wife Christine, 38, and 7-year-old daughter Amber at their Palmerston North home in August 2000.
This morning's Supreme Court judgement is the last in a long string of appeals.
The appeal bid hung on a single point - whether the Court of Appeal was wrong in choosing not to overturn Lundy's convictions when part of the evidence used to secure them was found to be inadmissible.
Lundy's lawyer, Jonathan Eaton QC, criticised the use of mRNA evidence at an earlier hearing, calling it "novel and junk science".
The evidence was used to tell the jury the brain or spinal tissue found in tiny specks on Lundy's shirt was likely human, rather than from an animal.
The method for analysing the brain tissue had "never been used before, never been used again", and the evidence based off it had been found inadmissible by an earlier court ruling.
"The name Mark Lundy has become synonymous with flawed expert opinion, flawed science and miscarriage of justice," Eaton said.
The Crown dug up the mRNA evidence after the Privy Council decision to "fill a gap" in the science linking Lundy to the murders, he said.
"Once you've got the link that it's human, it's game over."
Christine and Amber Lundy were found hacked to death at their home, likely with an axe or tomahawk. 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 his first trial whether or not it was physically possible for Lundy to have travelled between Wellington and his family home in a time that would have allowed him to be in the house at the time of the murders.
Justice Mark O'Regan read out the Supreme Court judgement this morning in Wellington. He said the panel of judges on the case all agreed to dismiss the appeal.
Friend and supporter Geoff Levick told the Herald he hadn't finished reading the full decision yet, but he was "not surprised", because the defence "wasn't presented properly in my opinion".
He would not comment further than that until he had time to read and process the full decision.
In a statement from Lundy's lawyers, Eaton, and Julie-Anne Kincade QC, they said Lundy continued to maintain his innocence.
"Naturally, Mr Lundy, his legal team and his supporters who have all worked so tirelessly to both establish his innocence and uphold his absolute right to a fair trial, are very disappointed with the decision of the Supreme Court to dismiss his appeal against conviction."
"The prosecution of Mark Lundy has been something of a testing ground for new or novel science never previously advanced in any court of law.
"It is frustrating and very disappointing that Mark Lundy has never had the opportunity to have his guilt or innocence determined by a jury who were not exposed to bad science – scientific opinion that a jury should not have heard.
"As science develops, so does the international debate and controversy over the willingness of courts to allow new science to play a role in criminal prosecutions.
"History tells us that it is the passage of time that often provides the opportunity to demonstrate the weaknesses and dangers in relying on what is otherwise said to be
novel but reliable scientific opinion."
Today's decision marked the end of the formal legal process for Lundy, but his supporters would not give up the fight on his behalf, they said.
"Mr Lundy's case has troubled the legal system in New Zealand for nearly two decades. The issues that Mr Lundy was permitted to raise throughout the appeal process were necessarily constrained by legal process. Our newly established Criminal Cases Review Commission will not be so constrained. This is not the end of the road in Mr Lundy's fight to establish he has suffered a miscarriage of justice."
The court cases
Lundy was first convicted of the murders in 2002, and his first appeal attempt resulted in the court increasing the non-parole period of his life sentence to 20 years.
His conviction was quashed by the Privy Council in 2013, which ruled there were problems with the analysis of the brain tissue found on Lundy's shirt, as well as with the time of death.
In a 2015 retrial at the High Court in Wellington, Lundy was again convicted of the murders.
He appealed to the Court of Appeal last year, which found the evidence around the brain tissue should not have been presented to the jury, but decided to uphold the convictions anyway.
The Crown argued Christine Lundy's brain tissue was found on the polo shirt her husband 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.