David Harold Eastman is serving a life sentence for the 1989 murder of Mr Winchester.
He has always protested his innocence and a fresh inquiry into his murder conviction is due to wrap up today.
His lawyer Mark Griffin has already told the inquiry there was a miscarriage of justice because the prosecution relied heavily on the now discredited forensic case.
He says there was also an emphasis on the credibility of forensic scientist Robert Collins Barnes.
Mr Griffin says as evidence to the inquiry discrediting Mr Barnes shows, he was not the doyen of forensic scientists that he had been portrayed.
But prosecutors and police say even without the forensic evidence the circumstantial case is overwhelming.
However Mr Griffin told the inquiry there is a body of evidence suggesting a group with mafia connections had a strong motive for the murder.
Details about those circumstances have been suppressed by the inquiry.
Mr Griffin says that evidence is a counterbalance to the circumstantial case.
He has also urged the inquiry to deliver adverse findings against both Dr Barnes and the police, who he says should have inquired further when they heard Dr Barnes was subject to disciplinary action in Victoria.