A detective who worked on the Sounds murder case now says he is ashamed to have been part of the police investigation - and believes Scott Watson is innocent.
The claims from former officer Michael Chappell come as the lawyer working to free Watson from jail says a number of police officers who investigated the disappearance of Ben Smart and Olivia Hope in the Marlborough Sounds have come forward to share their doubts.
Barrister Greg King plans to lodge a petition with the Governor-General next year, and would like to use testimonies from officers worried about how the murder investigation was conducted.
Investigative journalist Keith Hunter, who wrote the book Trial by Trickery, says he has also spoken to two high-ranking former police officers with growing doubts over Watson's guilt, as well as Chappell.
However police deputy commissioner Rob Pope has dismissed the claims from Chappell, who he says left the police force "under a cloud" and remains disaffected.
In a statement, Pope said: "Chappell's involvement in the Sounds inquiry was right at the start, short-lived and extremely peripheral.
"Because of this, his comments are made without full knowledge of the detailed planning, taskings and overall direction associated with the six-month-long inquiry."
Chappell, who worked on the inquiry in the first six weeks after Ben and Olivia went missing from the Marlborough Sounds in 1998 has said: "I believe Scott Watson is innocent."
He says Watson quickly became the prime suspect, even though police were searching for a ketch that water-taxi driver Guy Wallace said he dropped the pair off at with a "mystery man".
However, Chappell says the inquiry focus soon switched to Watson when he was mentioned as a potential suspect; a so-called loner who owned a boat and was at Furneaux Lodge on New Year's Eve.
The "mystery man" was described as wiry, with two days of stubble and shaggy dark hair. But photos taken on New Year's Eve show Watson clean shaven, with short, cropped hair.
"The focus never changed back. They even discussed at one of the briefings that he didn't fit the description, but that was glossed over," Chappell said.
On most nights, Chappell said the police would have briefings, sometimes in Pope's room at the motor-inn, sometimes in the garages out the back as the detectives were "paranoid" about the media listening.
Chappell worked as the systems manager looking after the computer system and answered hundreds of calls about the "mystery ketch" from the 0800 phone number for public tips.
But after only a few days of receiving calls, he said the inquiry team was told to ignore them
Pope has refused Herald on Sunday requests for an interview over the past three weeks and would not comment further after issuing his statement last night.
After a five-month investigation that focused on Watson and his sloop Blade, the 26-year-old was arrested and charged with double murder. He was convicted in 1999.
That same year, Chappell left the police force to set up his own computer forensics company, but was later charged with 10 dishonesty offences, including attempting to pervert the course of justice.
Convicted on some of the charges in 2002, Chappell ironically served a year in the same prison as Watson.
The former officer, who the Herald on Sunday tracked down rather than vice versa, says his public criticism of the murder investigation is not to retaliate against the police, but because he believes Watson is innocent.
"I don't have an axe to grind. I am not saying that all investigations or police in general behave like this. There are some really great police officers out there, who do their job by the book and to the best of their ability," Chappell said. "But when the pressure comes on, from above, then things change."
Greg King, Watson's lawyer, agreed with Chappell's opinion that the police had tunnel vision when investigating the disappearance of Smart and Hope.
A number of police officers who worked on the murder inquiry had approached King with similar concerns.
"The police were playing the man, not playing the ball. From very early on they focused on Scott Watson to the exclusion of any other possibility.
"Any other evidence was discarded or discounted," King said yesterday.
The only legal avenue remaining to Watson is to lodge a petition with the Governor-General, who can grant a Royal Pardon or refer the case back to the Court of Appeal.
A petition would likely be filed within the next 12 months, King said. Two officers involved in the case had approached King with concerns after reading Hunter's book Trial by Trickery, and he hoped to talk to another, who he said had "explosive" evidence.
A fortnight ago, Olivia Hope's father Gerald told the Herald on Sunday that he had serious doubts over Watson's double murder conviction.
"What we got was a conviction but we never got the truth. And that's the part that still really rips me up," Hope said. "Nothing ever was confirmed, it was all circumstantial, there was no hard evidence. And that's where my greatest doubts lie.
"I'm not saying [Scott Watson] is not guilty. What I'm saying is let's clear up the doubt."
He said the Crown case was based on circumstantial "emotional" evidence which tugged on the heart strings of the jury and his family.
"We were so emotionally tied up as it unravelled that we were blinded. But it was pure theatre. And parts of that story are shallow - incredibly shallow."
Two other key police witnesses - Wallace, and Furneaux Lodge bar manager Roz McNeilly - have also retracted their key evidence identifying Scott Watson as the "mystery man" in the bar, and believe he is innocent.
Watson's father Chris told the Herald on Sunday yesterday that several police officers who were in Blenheim during the murder investigation had expressed their concerns to him.
"There are a lot of people out there who are worried about it [the conviction]. It doesn't take a lot to stir it up. It's on people's minds which is good."