The rifle used in the Bain family murders was centre stage again in the High Court in Christchurch on Thursday.
Retired forensic scientist Dr Peter Hentschel was told that the rifle he had tested in 1994 had been retested in 1997 by other Environmental Science and Research people, and his findings and the new findings were compared by defence counsel Michael Reed QC.
In the first trial of David Bain, Hentschel told the jury that he saw four fingerprints on the forearm of the rifle.
"Now two of the four fingerprints have vanished," Reed says.
"I don't know why they only found two, I did not remove two fingerprints," Hentschel says.
He agrees with Reed that there were no diagrams or notes taken about the tests on the rifle, so that any new tests would have nothing to be compared with.
He says his work was of the standard that things were carried out in those days.
He took no notes or photographs of any of the exhibits or work he did at the scene over four days of the first week on the murder scene at Every Street, Dunedin, and says he was relying on the officer in charge of each room to take the notes.
He was told that other scientists now say there is insufficient recording for re-interpretation of his work to be done.
He says he believed he had done sufficiently.
The samples he used for his testing have all been destroyed.
He tested a skin sample found in Stephen Bain's bedroom, and at the first trial told the jury that it was of such a shape as it could have come from the knee of David Bain, but it could not be conclusive.
It is now known, because the sample was kept in Melbourne and retested, that the skin came from Stephen Bain.
On re-examination, crown prosecutor Keiran Raftery asked Hentschel if he had been asked by anyone to help them interpret his work.
He says he had not been approached by experts or defence counsel.
David Bain denies charges of murdering five members of his family at their family home in 1994. The retrial before Justice Graham Panckhurst and a jury is in its 18th day.