New evidence has emerged pointing strongly to Robin Bain being the murderer of his wife and three of their children, a television documentary has claimed.
A string of forensic and gun experts told TV3's 3rdDegree that parallel marks on the thumb of Robin Bain are consistent with those picked up when loading a magazine on a rifle which has recently been fired.
One of those experts was gunsmith Robbie Tiffin who said: "If these marks are from a magazine and loading a magazine, then you're the guy who pulled the trigger. It looks to me like Robin Bain loaded [it]."
The only surviving member of the family, David Bain, was charged with murder and served 13 years in prison before being freed when a new trial was ordered.
He was found not guilty at the second trial in 2009.
The "new" evidence has been hiding in plain sight since the five members of the Bain family were slain in 1994.
Waikato businessman David Giles discovered marks in photographs from the case on the fingers after following a link off an online discussion about the murders. He recognised the marks instantly as matching the carbon tracks left on his own thumb when loading a magazine while rabbit shooting with a .22 rifle.
The back-blast of burned gunpowder coats the rifle parts, meaning anyone loading new rounds into the rifle picks up traces of the grimy residue from the top of the magazine where bullets are stored. He contacted Mr Karam who made his own checks with firearms experts which confirmed the initial impression.
Mr Karam applied to the High Court for permission to carry out tests with the murder weapons, conducted under Crown supervision. Repeated tests produced exactly the same markings - and later tests matched the distance between the marks on Robin Bain's thumb with the distance between the top of the magazine.
A spokesman for police said it had not been approached by TV3 about the content of the show so had no idea what it was about. He said no comment would be made until tomorrow - if at all.
Justice Minister Judith Collins was in the United States - a spokeswoman said she would not be watching the show. "It would be inappropriate for the Minister to comment while this matter is still before the courts."
David Bain filed an application for compensation in 2010. The application was investigated by Canadian Supreme Court judge Ian Binnie who said Mr Bain was probably innocent but his compensation should paid because of "the egregious errors of the Dunedin Police that led directly to the wrongful conviction" following which he was imprisoned.
These photos show how similar marks were left on fingers in similar situations:
