A forensic expert has admitted he may have misled the inquest on ACT police chief Colin Stanley Winchester and allowed ''unacceptable confusion'' in the labelling of gunshot residue taken from David Eastman's car and the murder scene.
Robert Barnes was a Victorian-based forensic scientist whose analysis of gunshot residue was critical in linking Eastman, then a suspect for the murder, with the crime scene.
His work compared particles found in the boot of Eastman's Mazda with those found on the driveway on which Mr Winchester was found shot dead in his car. Eastman was eventually convicted by a jury in 1995 and has remained in prison since, serving a life sentence.
But Mr Barnes' work has come under attack in the latest Eastman inquiry, which was ordered after fresh doubt was raised about the conviction.
On Thursday, Mr Barnes faced further questioning from counsel assisting Liesl Chapman, SC, about whether he misled the inquest into Mr Winchester's death.
Mr Barnes had described the particles found at the scene as ''indistinguishable'' from those in Eastman's Mazda and from test firings of PMC-brand ammunition.
Ms Chapman asked last week whether that was misleading, given there was not enough evidence to draw the conclusion and given that the gunshot residue had not been excluded from several other ammunition types.
Mr Barnes agreed it was ''too strong a conclusion to draw'' and that it could have been misleading, but said he thought he had qualified it to the coroner.
Ms Chapman challenged that as well. ''If you can take it on the assumption that you didn't, Mr Barnes, and what you conveyed to the coroner on a number of occasions, was that the comparison between the scene and the Mazda boot was such that they were indistinguishable,'' she said.
''Do you agree that if you had added, as you should have added, that it was also indistinguishable from all other types of green flattened-ball, partially burnt propellant, that would have made a different impression upon the person listening to what you were saying?''
Mr Barnes agreed it would have.
On Friday morning, Mr Barnes was questioned by Ms Chapman over a mix-up with the labelling of forensic samples taken from Eastman's Mazda and from the scene.
''Mr Barnes, this data is a completely unacceptable confusion of information for forensic casework, isn't it?'' Ms Chapman asked.
''What has been confused here is the accused's car with a scene sample. It's completely unsatisfactory, isn't it?''
Mr Barnes admitted the labelling was confusing now but said he knew where the samples had come from while he was doing the work.
Mr Barnes is suffering from serious health conditions and is battling malignant melanomas.
He was forced to take a break from his evidence because of his health on Friday, and Acting Justice Brian Martin adjourned the hearing until Tuesday. If Mr Barnes is not well enough to continue, the inquiry will reconvene to discuss other matters on Wednesday.
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