Explainer: the controversial case of Scott Watson
After 18 years, convicted murderer Scott Watson has given his first media interview - and maintains he had no involvement in the disappearance of Ben Smart and Olivia Hope.
WHAT HAPPENED TO BEN SMART AND OLIVIA HOPE?
Ben Smart, 21, and Olivia Hope, 17, were among hundreds of party-goers at Furneaux Lodge in Endeavour Inlet in the Marlborough Sounds on New Year's Eve 1997.
Water taxi driver Guy Wallace said that in the early hours of January 1, 1998, he dropped the pair and a man at a two-masted yacht in the inlet.
Smart and Hope were never seen again and their bodies have not been found.
HOW WAS SCOTT WATSON IMPLICATED?
Scott Watson was also in the Marlborough Sounds, on his single-masted sloop, Blade.
Although neither he nor his boat matched Wallace's descriptions, Watson was arrested in June 1998.
His trial, in the High Court at Wellington, ran from June 1999. He was found guilty of the pair's murders and sentenced to life in prison with a 17-year non-parole period in November 1999.
Watson's response to the court on being found guilty was: "You're wrong".
WAS THE JURY WRONG?
Watson still maintains his innocence, and says he never met Smart and Hope.
"I don't know where Ben and Olivia are," he recently told North and South. "I've never met them, never seen them."
"They definitely never came on my boat and I definitely didn't murder them. And they've basically dumped me in jail for half my lifetime, it must be coming up, for something I haven't done."
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Watson believed he was an "easy target" for police.
"I think it was because I had a criminal record and I was [at Furneaux Lodge] alone and I left alone.
WHY ARE THERE STILL DOUBTS IN THE CASE?
Several pieces of evidence from the original trial are disputed:
* The two-masted ketch:
Much of the evidence during his trial centred on the boat Smart and Hope were last seen boarding. The Crown argued it was Watson's one-masted yacht, but Wallace maintained it was a two-masted ketch.
Wallace had also described a man with lots of stubble and bushy, longish hair, but photographs of Watson on New Year's Eve day show him as clean-shaven with short hair.
In 2003, he told a documentary team that Watson was "definitely not" the man he took in his water taxi that night.
* Veracity of hair evidence:
Two hairs, which were "strongly indicative" of having come from Hope, were found on a blanket on Watson's home-built sloop, though the defence raised doubts about the accuracy and reliability of DNA tests.
* Witnesses recant:
One witness, known as Secret Witness A, claimed Watson confessed to him in jail, but later recanted, before changing his evidence twice more.
Bar manager Roz McNeilly, who served a "mystery man" at Furneaux Lodge on New Year's Eve, changed her trial evidence and signed an affidavit saying the man she served was not Watson, after seeing a photo of Watson that was taken that night.
WHAT'S HAPPENED SINCE 1998?
Watson appealed his conviction in December 1999, based on one claim of fresh evidence and six alleged trial errors. In 2000, the Court of Appeal ruled no miscarriage of justice was demonstrated and dismissed the appeal.
In 2003, the Privy Council rejected another appeal from Watson.
In 2013, Governor-General Sir Jerry Mateparae turned down Watson's request for the royal prerogative of mercy, on advice from then-Justice Minister Judith Collins.
Collins said a QC's review of the case concluded "that nothing provided in support of Mr Watson's application created a real risk that Mr Watson was wrongfully convicted".
WHERE IS THE CASE AT NOW?
Earlier this year, Watson's legal team said they would seek a judicial review of Mateparae's decision, and another Privy Council appeal was a possibility.
Watson became eligible for parole this year. The Parole Board declined to release him because it considered he remained an undue risk to the safety of the community.
In June, this year a judge in the High Court at Christchurch overturned a ruling by the Department of Corrections, which had refused a request by Watson to be interviewed by North and South journalist Mike White. A story based on the interview was published on Monday.
Earlier this month, the discovery of a sunken wreck in the Marlborough Sounds sparked speculation it might be the boat where Hope and Smart were last seen.
Coastguard Marlborough president Dick Chapman said he doubted that was the missing clue in the murder case: "There's been all sorts of stories floating around but I don't tend to believe everything."
Police were yet to confirm the boat's identity, but said it was neither a yacht nor a ketch.
CASE SCRUTINISED
The evidence used to convict Watson has also been picked over in minute detail by members of the public.
Ben and Olivia: What Really Happened, a book by journalists Jayson Rhodes and Ian Wishart published soon after the trial, offered a detailed critique of the trial. It concluded "it would be a brave person who believes guilt has been proven beyond all reasonable doubt".
In 2000, Silent Evidence: Inside the Police Search for Ben and Olivia, a book by journalist John Goulter, concluded Watson did it. Police inquiry head Rob Pope contributed a foreword.
The Marlborough Mystery, by Auckland yachtie Mike Kalaugher, concluded that "the mystery of Ben and Olivia has not been solved".
Keith Hunter's TV documentary, Murder on the Blade? in 2003 criticised the Crown case. Key Crown witness, water taxi driver Guy Wallace, told Hunter he no longer believed Watson was the man he dropped off at a yacht on New Year's Day.
Hunter's book, Trial by Trickery: Scott Watson, the Sounds Murders and the Game of Law, in 2007, provided a detailed critique of the Crown case and the police investigation.