David Eastman

David Eastman. Photo: Andrew Taylor

A forensic scientist whose crucial analysis of gunshot residue linked David Eastman to the murder of the ACT’s police chief is trying to thwart a detailed investigation of his work.

But Robert Barnes’ challenge has stumbled at the first hurdle, with his lawyers failing to convince the head of a probe into Eastman’s conviction that such an investigation was outside the inquiry’s scope.

As he dismissed the bid by Mr Barnes, Acting Justice Brian Martin warned the inquiry into Eastman’s conviction for the 1989 murder of Assistant Australian Federal Police Commissioner Colin Stanley Winchester had already unearthed issues that must be fully investigated.

He warned there had been a ‘‘great deal of controversy’’ attached to the case since the day of the murder, and this must be put to rest.

‘‘Otherwise it will continue to fester for many years to come,’’ he said.

The murder of Mr Winchester is one of the most notorious crimes in the ACT’s history, involving the highest ranking police officer to ever be killed in Australia.

But Eastman has always maintained his innocence, and an inquiry is being held into his conviction following a lengthy trial in 1995.

The work of Mr Barnes, a Victorian-based forensic scientist, was a critical part of the Crown’s case, and linked gunshot residue found at the murder scene - in Mr Winchester’s hair, on his Ford, and on the driveway - with particles discovered in the boot of Eastman’s car.

That evidence was used to put Eastman at the scene in ‘‘highly incriminating circumstances’’, the inquiry into Eastman’s conviction heard on Monday.

But a key role of the inquiry was to investigate a series of potential reliability and veracity issues with Mr Barnes’ testing and analysis of the gunshot residue.

The inquiry’s terms of reference require it to look at whether the prosecution neglected its duty to disclose information casting doubt on the work of Mr Barnes to the defence before or during the 1995 trial.

They also require it to look at possible issues with Mr Barnes’ finding that a silencer was fitted to the murder weapon, and also to examine new protocols that guide how ‘‘low level’’ gunshot residue can be used as evidence in court.

The inquiry is also tasked with investigating the possibility that gunshot residue evidence was contaminated innocently, possibly because some particles were photographed in a room that was located near a firing range and that had been used to store exhibits for an unrelated murder.

But lawyers for Mr Barnes on Monday morning mounted a challenge to prevent the inquiry conducting a comprehensive investigation of the forensic scientist’s work.

They said such an exercise would be well outside the inquiry’s scope, and that Mr Barnes’ legal team had been taken completely by surprise when they realised on Friday that such evidence was going to heard.

His lawyer said it was a ‘‘misconcieved, bootstraps attempt to open things that are not in the terms of reference’’.

But Acting Justice Martin found against Mr Barnes in an immediate ruling, saying the scientist’s challenge overlooked the ‘‘total effect’’ of the terms of reference.

‘‘In my view it should not be read as limited in the way suggested,’’ Acting Justice Martin said.

The inquiry’s head went on to say the information unearthed on potential issues with the gunshot residue went to critical parts of the evidence at Eastman’s trial, and were of sufficient importance that they should be fully investigated.

He said the investigation may not end up establishing any reason to doubt the reliability of the evidence, and warned against trying to predict the outcome of the inquiry’s investigation.

Mr Barnes’ lawyer then signalled they would appeal the decision, and sought to prevent a Northern Ireland-based forensic scientist, Dr James Wallace, giving evidence until the challenge was resolved.

They are concerned Dr Wallace’s evidence will hurt the professional reputation of Mr Barnes, and argue it would be illegitimate for the inquiry to continue a detailed investigation of his work.

Acting Justice Martin refused to prevent Dr Wallace from giving evidence, but applied numerous gag orders that prevent Fairfax Media from publishing information about his reports and oral testimony.

Those gag orders may be lifted once Mr Barnes’ challenge is resolved.

The inquiry is continuing this week.