David Bain trial: Cop admits mistake over lens location

David Bain's family home burnt down about two weeks after his parents and three siblings were found dead. File photo / NZ Listener

The location of a lens from a pair of glasses in the home of David Bain has come under scrutiny again with a court witness who has previously sued for defamation over it.

Milton Weir, a detective sergeant in June, 1994, when investigating the deaths of Bain's parents and three siblings, agreed in the High Court today that he had made a mistake about exactly where the lens was found in the bedroom of David's brother, Stephen, 14.

The case against David Bain, 37, is that the lens came from the glasses he was wearing when he was involved in a struggle with Stephen.

David Bain is accused of shooting dead his family, but his defence team say it was his father Robin who killed them, before turning the rifle on himself.

Exactly where the lens was found by Mr Weir, in relation to an ice skate on Stephen's bedroom floor, is considered important as to whether it was dropped there on the day of the killings, or was left there earlier.

Mr Weir agreed today with Bain's lawyer, Michael Reed QC, that he sued Bain supporter Joe Karam for defamation over an inference in a book that he may have lied about certain aspects, and in particular where the lens got to.

He said he also sought a police investigation into the claims made by Mr Karam.

Mr Weir had originally "stuck to his guns" over where he thought the lens was found, but later his mistake was blamed on an optical effect.

When he found the lens, he thought it could be linked to a pair of glasses in David Bain's room, but was not sure until later.

"So it turned out to be an important find".

The court also heard today that tomato sauce was used in police reconstructions in the Bain home after the killings.

Mr Weir said he did not believe that any of the photographs presented in court evidence contained tomato sauce, but agreed with Mr Reed he could not be certain.

Earlier Mr Weir agreed with the defence that important evidence was lost when the Bain home burnt down about two weeks after the deaths.

Mr Weir also said it was fair to say he was disappointed at the number of people that had gone through the Bain family home on the day of the killings.

Mr Weir, who said he initially viewed the deaths as a murder-suicide, was asked by defence lawyer, Michael Reed QC, about five bloody footprints found in the house after the bodies were found. He agreed this was important evidence.

"The footprints we found, there is a very good chance they were made by the killer, yes. But there could be other explanations for them," he said.

He agreed with Mr Reed that he was present when ESR scientist Peter Hentschel conducted luminol testing to observe the footprints.

But he said the areas of carpet with the bloody footprints where found were not removed before the house was burnt down. Other areas of carpet in the house had been.

"I believe if (Peter Hentschel) had considered it necessary, he would have advised me to cut the carpet out. He didn't. I never knew the house was going to be burnt down.

"We don't have the pieces of carpet, I accept that."

Two of the biggest bloody footprints were measured at 280mm. Socks belonging to both David and Robin Bain were later measured as comparisons.

Asked if the only photographs taken of the sockprints were of poor quality and "useless", Mr Weir said: "They were useless".

Mr Reed asked if Robin's foot was measured at 270mm in the mortuary, to which Mr Weir responded: "If you say so. I certainly wasn't there".