He's been behind bars for 26 years but on Monday Scott Watson will again fight for his freedom when his appeal starts in Wellington.
Watson - who is aged in his early 50s - has spent around half his life in prison for the murders of Ben Smart and Olivia Hope.
It's a crime he says he didn't commit.
Smart, 21, and 17-year-old Hope were celebrating the New Year with around 1500 other people at a party at Furneaux Lodge in the Marlborough Sounds.
Shortly after, in the early hours of January 1, 1998, the young friends vanished without a trace.
Following a five-month investigation, in June 1998, Watson - who was a boatbuilder from Picton - was charged with their murder.
In 1999, after an 11-week trial in Wellington, he was found guilty of killing Smart and Hope.
The only bit of physical evidence in the case and trial related to two hairs the Crown alleged were found on a blanket on Watson's yacht, Blade. The prosecution said DNA analysis strongly supported the proposition the two hairs were those of Hope.
At the trial, Watson's counsel questioned the hair samples.
The defence said there was a strong possibility of inadvertent transfer of the hairs at the ESR Laboratory when both the reference hairs known to have originated from Hope and the hairs from the 'tiger blanket' from Watson's yacht were examined.
The defence also contended the hairs on the blanket had been screened on two previous occasions without an examiner noticing "the two crucial blonde hairs".
Aged 26 at the time, Scott Watson was sentenced to life imprisonment with a minimum non-parole period of 17 years.
Watson denies ever even meeting Smart and Hope and has always maintained his innocence.
The bodies of the pair have never been found, nor have any of their possessions.
After his trial Watson appealed against his conviction and sentence but this was dismissed by the Court of Appeal in 2000.
His application for leave to appeal to the Privy Council was also declined in 2003.
In 2008, Watson made his first application to the Governor-General for the exercise of the Royal prerogative of mercy.
The Ministry of Justice instructed Kristy McDonald QC to advise on that application.
She examined if Watson's application contained any fresh evidence that would raise a real doubt about the safety of Watson's convictions.
McDonald was not satisfied that any of the new evidence was fresh and credible.
The application was denied by the Governor-General in 2013 on the advice of the then-Minister of Justice.
Watson has also been denied parole a number of times.
"We seem to have a Parole Board that's hell-bent on wringing a confession out of him," said his father Chris Watson.
Now his son has a chance to overturn his convictions in his appeal starting on Monday.
Chris Watson is travelling to Wellington for it, as is Scott's brother Tom.
The 76-year-old regularly speaks to his son in prison over the phone and in recent months they've been discussing the appeal.
"There's been a lot of work by a lot of people to get here," Chris Watson told Newshub.
"I maintain Scott is innocent. It's a case that hasn't been forgotten about. I'd like to get my hopes up," he added.
University of Auckland Law Professor Mark Henaghan said there are three possible outcomes to the appeal.
One is that the appeal is dismissed. Another is that the court "finds a miscarriage of justice which means the convictions are quashed and court orders a retrial," said Professor Henaghan.
The third possible outcome is that Watson's convictions are quashed but no new trial is ordered which means he walks free.
