Defence claim that David Bain's fingerprints on the rifle used to kill five of his family in 1994 were not in blood was the subject of rebuttal evidence from the Crown yesterday.
Kim Jones, head of the police fingerprint section, was the last witness called on the 54th day of evidence in David Bain's retrial for the murders.
Although Mr Jones gave evidence much earlier in the trial, Justice Graham Panckhurst granted a Crown application for his recall to clarify points raised by Carl Lloyd, a British fingerprint expert called by the defence last week.
Mr Lloyd completed his evidence in chief on Friday but his cross-examination was delayed until yesterday so the Crown could consult Mr Jones about some of the matters raised.
And because Mr Lloyd had to return to the UK last weekend, the cross-examination by Crown counsel Kieran Raftery yesterday was by video link.
That caused a few problems at times when Mr Lloyd was asked to look at photographs on the video screen of David Bain's fingerprints on the murder weapon.
But he maintained his stance that Bain's fingerprints on the rifle stock were not positive prints made by bloodied fingers, as contended by Mr Jones.
He based his opinion on the fact the ridges of the prints showed as white in a black and white photograph.
If the prints were in blood, the ridges would show as black in such a photograph, he said.
And he believed the print was a "latent" print rather than a print in blood and that it had been chemically enhanced before it was photographed.
But he agreed with Mr Raftery that for anyone looking at the rifle with a naked eye, prints in blood would be expected to show reddish coloured ridges.
Mr Raftery said Mr Jones, as well as ESR scientist Peter Hentschel who examined the rifle very soon after the shootings, both believed what they saw were prints made by a hand with blood on it.
Another ESR scientist who tested a substance from the area of the prints had obtained confirmation of the presence of human blood although the sample was too small for blood grouping.
Given the blood sample was taken from the area where David Bain's middle fingerprint was found on the rifle, Mr Lloyd agree there was "a good chance" the sample captured whatever contaminant the print was in.
But, in answer to defence counsel Michael Reed QC, Mr Lloyd said if tests carried out by Australian scientists found no human DNA under the prints, that indicated to him "there was no blood there".
And he confirmed his opinion that prints in blood would show black ridges when photographed under a white light.
"There's no way you will get white ridges if there's blood," Mr Lloyd said.
But Mr Jones told the court he had conducted his own tests after hearing Mr Lloyd's evidence in chief last Friday.
He used his own bloodied thumb to make prints on the wooden stock of a rifle.
Those prints were then photographed under the white light of a polilight device.
The coloured photograph taken on a digital camera showed the fingerprint ridges as white.
And when a black and white version of the same photograph was created, the ridges were also white.
When comparing the photograph of Bain's fingerprints on the murder weapon with the photographs of the prints he put on the rifle stock last weekend, the ridges were exactly the same "They showed as white", Mr Jones said.
He had not treated his fingerprints with chemicals of any kind before they were photographed, he told the court.
To make the comparison with the prints taken from Bain when he was arrested, which showed black ridges from the ink used, with the picture of the print from the rifle, the colour of the ridges had been reversed from white to black "so we could compare like with like", Mr Jones said.
But he did not chemically enhance Bain's prints on the rifle in any way before they were photographed in June, 1994.
And an assertion by Mr Lloyd that the print was a latent one which had been treated with a chemical was "categorically false", Mr Jones told the court.
He said he was alerted to the fact the prints on Bain's rifle were in blood because they appeared red in colour.
