The inquiry has poured over a mind-boggling volume of information, hearing from a huge number of witnesses and viewing roughly 200 exhibits, some hundreds of pages long.

From the sea of evidence, chartered chiefly by Acting Justice Brian Martin and Counsel Assisting Liesl Chapman, SC, have arisen serious questions, including about aspects of the police work, forensics, and the non-disclosure of material to the defence.

The inquiry was ordered after fresh doubt was raised about the 1995 conviction of David Harold Eastman for the shooting murder of ACT police chief Colin Stanley Winchester in 1989.

Mr Winchester was shot twice in the back of the head at close range as he moved to get out of his car, which he had parked in his neighbour’s driveway.

The crime was one of Australia’s most notorious, and involved the assassination of the highest-ranking police officer in the country’s history.

The Australian Federal Police proclaimed it to be the ‘‘end of innocence’’ for the force, and the death sparked years of police work, which would later be described by the sentencing Supreme Court judge as ‘‘one of the most skilled, sophisticated and determined forensic investigations in the history of Australia”.

Yet Eastman has maintained his innocence to the crime for all of the 18 years he has now served of his life sentence.

The inquiry has heard evidence on 19 terms of reference since November last year.

It has looked at issues of whether the applicant’s fitness to stand trial was properly considered, whether prosecutors complied with their obligations to disclose material to the defence, and an alternative hypothesis of involvement by figures linked to Italian organised crime.

Evidence has also been heard about the reliability of Eastman’s supposed confessions, made as he spoke to himself and recorded by bugs in his home.

The inquiry has looked at the conduct of police, including their long campaign of surveillance, the prosecution, and the trial judge.

One of the most critical questions raised in the inquiry, however, concerns the reliability of the forensic work, most importantly that of Victorian-based expert Robert Barnes.

Mr Barnes’ analysis linked gunshot residue in Eastman’s boot with the murder scene, which would prove a key part of the Crown’s case against the former public servant.

But the inquiry has subjected his work to painstakingly detailed scrutiny, forcing him to respond to allegations he was misleading about the strength of the evidence.

Mr Barnes is battling cancer and was too sick to keep giving evidence, but is expected to be sent a notice warning him he would be subject to adverse findings.

He has run out of funds for his legal team, and it is unclear how Mr Barnes will respond.

The inquiry is far from concluded.

It still needs to receive written submissions and hear oral submissions from all parties, before Acting Justice Martin delivers his final report.

The oral submissions will be heard next month.

The inquiry will continue on in the shadow of a challenge by the Director of Public Prosecutions before the full bench of the ACT Supreme Court.

That challenge concerns key decisions that created the inquiry and shaped its scope, and if upheld, could stop proceedings.

Acting Justice Martin said on Wednesday that parties should continue working on the inquiry, regardless of the decision the full bench of the ACT Supreme Court makes.