Police doubt marks seen on the fingerprints of Robin Bain are the result of him having loaded a gun before his death.
But David Bain supporter Joe Karam has rubbished the police conclusion.
Assistant Commissioner Malcolm Burgess yesterday released two reports in relation to the theory that marks seen in photographs of Robin Bain's thumb were caused by gun powder residue from the loading of a cartridge into a firearm magazine.
The claim, made through television programme 3rd Degree in June, prompted police to analyse original autopsy fingerprint forms and to test the weapon used in the Bain homicides.
Environmental Science and Research firearms expert Kevan Walsh assessed whether marks on Robin Bain's fingerprints were consistent with marks made by the loading of the gun.
He found the fingerprint marks were generally shorter and wider than those which resulted from testing the gun, but were within testing variations.
The marks were also not parallel, Mr Walsh said.
"In my opinion there is considerable doubt that the shape, dimensions and colour of the marks on Mr Bain's thumb are consistent with marks made as a result of loading a cartridge into a magazine," he said.
Mr Walsh also said the lack of appropriate scales and the orientation of Robin Bain's thumb in the original photos prevented a definitive conclusion about whether they were the result of loading a magazine.
Mr Burgess said the most likely explanation for the marks "would seem to be" pre-existing age or injury to the skin on Robin Bain's thumb.
"I am satisfied that this scientific analysis shows the marks highlighted by the 3rd Degree programme are anything but the 'game changer evidence' the programme claimed," he said.
Mr Karam said he was not surprised at the police conclusion.
He said the reports were part of an "academic attempt at rebuttal", which "failed miserably" to ask the necessary questions in relation to the Bain homicide case.
Those questions included how the marks on Robin Bain's fingers were made, why they were not evident in the original examination by pathologist Dr Alexander Dempster, and why Dr Dempster was not consulted in the recent analysis.
A spokeswoman for Justice Minister Judith Collins yesterday said Cabinet had put David Bain's application for compensation on hold at his request. The judicial review process was ongoing, and it remained inappropriate for the minister to comment, the spokeswoman said.
She said a substantive hearing was expected to occur later this year.