Gerald Hope believes he would know if convicted killer was guilty or innocent if he could see him.
Gerald Hope says he is still willing to meet the man convicted of murdering his daughter so Scott Watson can try to convince him of his innocence.
Mr Hope has renewed his offer to meet Watson, 41, who is serving a life sentence for murdering Olivia Hope and friend Ben Smart in 1998.
The pair, whose bodies have never been found, were last seen early on New Year's Day 1998, at Endeavour Inlet in the Marlborough Sounds.
Watson has tried to clear his name in the Court of Appeal and the Privy Council and finally through an appeal to the Governor-General for a pardon.
That appeal was yesterday declined - and that came as no surprise to Mr Hope.
"My view is the last door has closed for Scott Watson to appeal his conviction. That's pretty obvious."
He told the Herald last night: "Really, I've thrown a lifeline to him. Man to man, if he is innocent, I've suggested he fronts up. I'm more than happy to go down to Christchurch with his father present and we'll have a face-to-face discussion.
"If he can convince me he was not the murderer of our daughter then I'll be interested in supporting him."
It was an offer he'd made several times over the years.
"The doors have all closed, he's down to the last gasp. He's got two years until parole and there's no certainty he'll get that."
Mr Hope believed he would know if Watson was guilty or innocent when he saw him.
"I'm pretty convinced. Most of us when we talk to each other face to face you can pretty well sum a person up, can't you? So that's the bottom line for me. If he was genuinely remorseful or guilt-free I would reconsider my opinion."
Above all, Mr Hope wanted to know what happened to Olivia and Ben.
"What happened and where are they. I'm repeating myself constantly, but that's the bottom line for us."
Despite the latest legal setback, Watson's father Chris Watson still believes there is a "damn good argument" on why his son is not guilty.
A main argument of Watson's application was his submission that two important Crown witnesses - water taxi driver Guy Wallace and bar manager Roslyn McNeilly - had made statements changing their trial evidence relating to the identification of Watson.
"Their only witness to make identification comes out and says definitively this "isn't the guy" [then] it says something about the justice system - it doesn't matter if they have the right guy or not as long as they have a conviction. That's the trouble, the conviction has become the proof."
Mr Watson promised to fight on. "We're not stopping. As well as Scott they [the police] offended my sense of justice as well. There's an innocent guy in jail, he's been there for 13 years and the person who did this is still wandering around. And no one is interested."
A detective who worked on the inquiry, Michael Chappell, believes Watson is innocent and became the prime suspect too quickly.
Last night he said Watson looked nothing like the description police had of a mystery person on New Year's Eve.
He said hair samples discovered on a blanket on Watson's boat had been examined and nothing found. A second search found two hairs after the hair samples had been obtained.
"Two hairs would have come up. But here's the plastic bag either on top of the blanket or beside it and there's a cut in it ... That's the only things that convicted him really, the identification and the hairs."