The case of John Barlow, who after three trials was convicted of a brutal double murder, is one of the most troubling of the past decade and Sunday reveals there are serious flaws in the evidence that finally helped convict him.
On February 16, 1994, Wellington financiers Eugene Thomas and his son Gene were shot to death in their office. John Barlow was the main suspect, but it would take three trials and a court of appeal hearing before he was convicted.
A critical difference with the third trial was forensic evidence from the most famous investigation bureau in the world which linked Barlow to the murders. But now the basis for that FBI testimony has been seriously discredited.
Sunday has revisited the Barlow case and a parallel case in America.
The double murder was a ruthless, cold-blooded execution. Successful businessman Eugene Thomas and his son Gene were shot dead on the terrace in their own Wellington office building.
Suspicion inevitably fell on John Barlow - the last person to have a scheduled appointment with the Thomas' on the day they were murdered.
At the time Barlow acknowledged he was one of the prime suspects and he went public before his arrest.
"I just recall it being dim and then I saw the body lying on the floor...and that was the son...then I got closer and saw what appeared to be blood on the floor," Barlow says.
In the middle of the crime scene was Barlow's war-vintage CZ 27 pistol, which Barlow says he lent to Eugene Thomas snr for self protection.
Eugene was found lying slumped in a chair with a phone in his hand.
"He was dead...blood everywhere. My first thought was that somebody shot him with a shotgun... there seemed to be so much mess and blood," says Barlow.
But Barlow did not call the police. He says he just picked up the pistol and left the building because he was aware it could look bad for him.
"It sounds stupid, when you talk about it later. But perhaps people do stupid things at times and regret it later," he says.
The following day Barlow drove to the Happy Valley tip to dump rubbish. Police found the receipt in his glovebox and sifting through the rubbish they found Barlow's CZ pistol, ammunition and a cut-up silencer.
But Barlow was adamant it was not a murder weapon and he categorically denies killing anybody.
"No I certainly didn't...I've never killed anybody. And I haven't even killed animals for years and years...I've gone off the idea of blood sports but I do enjoy shooting at targets."
While he still claims he did not kill the Thomas', the court ruled that he did but only after two hung juries and an unprecedented third trial.
At that third trial new and significant evidence was introduced - forensic evidence linking Barlow to the murders - and the jury found him guilty. He was sentenced to life imprisonment.
But Sunday has obtained information and spoken to American experts who cast serious doubt on the forensic evidence - doubt that in turn raises questions about the safety of John Barlow's double-murder conviction.
In Teaneck, New Jersey, Angela Barlow - John's wife - has met with Jackie Behn to discuss her husband's case. Dr Behn is a criminologist by profession and a relentless campaigner for her brother Michael, who was convicted in 1997 for murder.
Behn is convinced the system got it wrong.
Angela Barlow has been married to John for 35 years and believes "he is not capable of doing such a terrible crime". She says she has never doubted his innocence.
Like Angela, Behn could make no sense of her brother's conviction and says it also seemed totally out of character.
"He had never had any trouble ever... no record...I couldn't believe it. It was really like someone socked me in the stomach...I couldn't believe it," says Behn.
It was Michael's interest in rare coins that would see him go down for murder. On the same day that he went to an address in South River, New Jersey to buy some rare and expensive coins the dealer was murdered - execution style with four shots to the back of the head.
Michael was accused and convicted, but apart from being in possession of the coins, there was no hard evidence linking him to the crime - no gun, no forensics and no eyewitness - so the prosecutors called in the FBI.
Charles Peters, an FBI expert and a key witness in the third trial of John Barlow, had also testified in the Michael Behn case.
In both trials he testified that the bullets found in the victim's bodies were virtual matches to the bullets belonging to both accused.
Sunday interviewed Michael Behn inside the Middlesex County jail, New Jersey where he is already 10 years into a 30 years to life sentence. Michael told Sunday he believes the FBI analysis was a key to the guilty verdict.
"It was very significant... you had...somebody with the weight of the FBI testifying, saying the bullets...that killed Mr Rose...came out of the same box of ammunition that I had at my house...yeah that links me to the crime," says Michael Behn.
Michael's sister listened intently to the evidence in court and was incredulous.
"I was just thinking: I can't believe that they could take bullets...of the billions of bullets that are manufactured on a yearly basis...and say that two particular bullets match...or that they could say they were made on the same day.
"...just intuitively I knew that this could not be right," says Jackie.
Jackie started digging, using her research expertise, and what she set in motion would overturn one of the cornerstones of FBI investigation - a process of forensic analysis dating back to the assassination of John F Kennedy in 1963. As in the Kennedy case, comparative bullet lead analysis would also be central to the prosecution case against John Barlow.
"The fundamental flaw of bullet lead analysis is that the analytical technique and opinions rendered from it were never validated," says Dr Fred Whitehurst, a former chemist at the FBI.
"No one ever determined in 40 years of the practice whether it was being done correctly. It was just accepted and they went from there," says Whitehurst.
He left the FBI after blowing the whistle over sloppy practices at the crime lab. It cost him his job and now he is a private practising attorney. Jackie Behn turned to Whitehurst for help.
"I don't enter into these investigations concerned about guilt or innocence," says Whitehurst.
"That is not the issue. I am a scientist. I am looking at: Is there an issue here? The issue then doesn't become 'is this person guilty or innocent?' It becomes whether they were treated fairly by the justice system."
Whitehurst is now part of what's known as the Forensic Justice Project, a legal unit that reviews and challenges forensic evidence. He enlisted the help of experts in their field to take on the FBI.
Rick Randich, a highly qualified metallurgist, was part of a team of independent scientists who doggedly analysed the process of bullet lead analysis and the way the FBI interpreted it in court.
"The FBI challenged me in the beginning, but I decided the only way to successfully challenge them was to get the data to show or to demonstrate that there were flaws in their assumptions," says Randich.
Working in his own time, Randich came to this conclusion about the FBI's testimony in the Michael Behn case: "It was a tremendous overstatement or extrapolation from virtually no data... and I said: 'This is not correct, you should not be able to use this to convict a man.'"
"Most of the criminalists in the field of forensics are chemists - they didn't know enough metallurgy and they didn't know enough about lead smelting," says Randich.
The research conducted by Dr Randich and the independent team of scientists began to record some significant victories - their findings were upheld by the US Academy of Sciences and this year the New Jersey Appeals Court granted Michael Behn a new trial. It could be the first of many case reviews.
Randich says of the John Barlow case: "From the information I was given, the third trial had the bullet lead evidence as the new evidence and that resulted in a conviction."
"If the bullet lead evidence was what swayed the jury, that should not have happened. The correct science should be re-explained to the court, and bullet lead evidence just cannot be used to convict a man."
For Angela Barlow in Wellington, the US findings have profound significance. She, her husband and their lawyer are convinced that the FBI evidence resulted in a guilty verdict.
"In our case, when you've had two hung juries and the juries cannot decide...and then they bring in the FBI on the third case; there is nothing new in the third trial but the FBI evidence," says Angela Barlow.
"I think that's what convicted John...it's just the mana of the FBI, they say that the bullets matched - how can you get past that?"
Charles Peters was the expert FBI witness in both the Barlow and Behn cases.
"Everybody in the courtroom was in awe of the FBI. This has never come to New Zealand before - it's a big thing," says Angela Barlow.
It was a big thing too for Jackie Behn in New Jersey - she did some research on Charles Peters.
"My brother's attorney and I both noticed that he didn't have a graduate degree. It seemed sparse the amount of training that he had, other than what he was doing at the FBI. So immediately it put up a red flag," says Jackie Behn.
None of this comes as a surprise to FBI whistleblower Fred Whitehurst at the Forensic Justice Project in Washington.
"Charles Peters is a good friend of mine. He is a technician who for 18 years worked in a crime lab - not as an examiner, not rendering opinions - but simply doing the science. He did the technology very well, but his interpretation of the data was severely flawed," says Whitehurst.
in California also studied Charles Peters' expert FBI testimony.
"It was bogus science then and it's bogus science now. They measured the compositions correctly, but their interpretation of the data was misleading," says Randich.
"Mr Peters is not testifying in a legally dishonest manner .. but I don't believe he is telling the whole truth."
What Charles Peters never made clear to the court was that he had learnt either before or after the trial that the bullet lead in the Barlow case happened to match the FBI's own reference bullets in Washington.
So theoretically the FBI's own bullets could be implicated in the double murder - along with any number of others.
"I do not know whether Mr Barlow is guilty or innocent," says Randich.
"My role is to determine whether the science being used as evidence is valid or not. In this case the interpretation of the bullet lead evidence was unfounded. The bullet lead evidence in the Barlow case cannot be used on its own to convict the man. It does not rule him out as a suspect, but it certainly cannot be used to convict him."
Last month in the US Capital the FBI formally announced it was discontinuing comparative bullet lead analysis.
The Bureau referred Sunday to a official press release which states the FBI still firmly supports this method of analysis, even though it has decided to stop using it.
It is all good news for Michael Behn in Middlesex County Jail - he now awaits retrial. The New Jersey appeals court concluded that the expert FBI testimony was based on "erroneous scientific foundations".
Behn's case now comes down to circumstantial evidence and he is cautiously confident about that.
And the Barlow's have not given up. Ten years on, John's case is once more under legal review. They have petitioned for a pardon which is currently before the Ministry of Justice.
"We just want this conviction quashed. You don't want a conviction for something you haven't done. Nobody should have to put up with injustice," says Angela Barlow.
With the discredited FBI evidence aside, two juries were unable to find John Barlow guilty or innocent.
"I was a typical fairly conservative person who thought that...they always get it right and if they get somebody it must be the person. And if he gets off well he's just dead lucky. But I'm not so sure now that it's quite as simple as that," says John Barlow.
The Justice Ministry's chief legal counsel has informed Barlow's lawyer that "good progress" is being made with processing the application.