David Eastman has launched his last-ditch bid to stave off a second trial for the 1989 murder of ACT police chief Colin Winchester.
The next two weeks will prove crucial in the long-running Eastman saga, which has dragged on in the courts in various forms for more than 25 years.
Mr Eastman was freed after a dramatic turn of events in 2014, when an inquiry uncovered shocking deficiencies in the forensic evidence used to link him to the murder scene during his 1995 trial.
He had spent 19 years behind bars.
He now faces a retrial for the murder, but on Monday began arguing his case to have the trial permanently stayed. Mr Eastman's legal team will use the stay application to argue that a retrial of their client cannot now be conducted fairly.
The lawyer who helped secure Mr Eastman's freedom, Mark Griffin, QC, told the ACT Supreme Court on Monday that their application to stay the retrial would rely on six grounds.
It will be argued that prosecutorial misconduct occurred in the original trial, particularly due to what the defence argues was a deliberate strategy to conceal weaknesses in the forensic evidence by not disclosing some information to Mr Eastman.
Mr Eastman will argue the Crown case is not strong enough to warrant a retrial, that the delay since the crime puts him in an unfair position, and that his personal circumstances, including mental health and time already served, weigh against a second trial going ahead.
The extensive media coverage of the case has also created prejudice against him, and the large expense to the taxpayer would be too exorbitant, his legal team argues.
A former ACT prosecutor involved in the 1995 trial of Mr Eastman, John Edward Ibbotson, was the first witness to be called in the stay application on Monday.
Mr Ibbotson was responsible, among other things, for marshalling the forensic evidence in the case against Mr Eastman, which linked the disgruntled Treasury official with the driveway where Mr Winchester was shot at point-blank range as he got out of his car.
The 2014 inquiry into Mr Eastman's conviction destroyed the reliability and credibility of the expert who conducted the gunshot residue analysis that made that link.
Mr Eastman's legal team is now arguing that the prosecution team, led by current NSW Supreme Court Justice Michael Adams, deliberately failed to disclose information that may have weakened or raised doubt about Robert Barnes' evidence during the 1995 trial.
Mr Griffin spent much of Monday questioning Mr Ibbotson about what he knew of the doubts about Mr Barnes, and how the prosecution went about disclosing information to the defence.
Mr Barnes was poorly qualified to conduct the testing, holding only a diploma in metallurgy, and was resistant to having his work reviewed by other experts.
Mr Barnes became belligerent when prosecutors told him they were going to have his work peer-reviewed by experts in the FBI, Israel, and Britain.
He relied on a masters student to build a database of gunshot propellant types, which he used to suggest that the propellant used in the killing was "indistinguishable" from particles linked to Eastman. That database was criticised by other experts engaged by the prosecution.
Many of the concerns about Mr Barnes were never disclosed to the defence, denying Mr Eastman the ability to attack the forensic evidence, which the Crown would go on to present to the jury as water-tight.
One new revelation to emerge in the stay application on Monday was a letter written by Mr Barnes, which criticised the overseas-based experts reviewing his work. That letter was not made available to the 2014 Eastman inquiry, despite subpoenas.
Mr Barnes' letter, which was headed with a caution that it be kept secret, highlighted the extent of the divisions between the forensic experts.
Yet it was never given to the defence, and was never shown to the jury.
Mr Griffin alleges the prosecution deliberately tried to prevent any indication to the jury that the forensic experts were in conflict.
He asked Mr Ibbotson about why the letter wasn't disclosed, and the former prosecutor replied that it was Mr Adams' responsibility.
"I was the bricklayer, he was the architect. He decided what would go and what wouldn't go."
"I was out of the loop."
Mr Adams is expected to give evidence later this week.
The prosecution's failures to disclose were found to be inadvertent by Acting Justice Brian Martin, who headed the inquiry into Mr Eastman's conviction.
The inquiry found that Mr Adams and others in the prosecution team "adhered to the highest standards of ethical conduct", and that "the failures to disclose were inadvertent and occurred as a result of a combination of circumstances".
Mr Eastman's defence is now trying to re-agitate the issue to prove prosecutorial misconduct occurred. The Crown, represented by Murugan Thangaraj, SC, said it would take something exceptional to move away from the inquiry's findings, which were relied upon by the ACT Supreme Court when it quashed Mr Eastman's conviction.
If the stay application fails, Mr Eastman will face another lengthy trial.