An inquiry into the murder conviction of David Harold Eastman recommends his conviction be quashed.

Inquiry head Justice Brian Martin found Eastman did not receive a fair trial and there has been a substantial miscarriage of justice.

Eastman has already served almost 19 years in prison for the murder of Australian Federal Police assistant commissioner Colin Winchester in 1989.

But the report could see Eastman soon set free if the ACT Supreme Court accepts the recommendations.

"The issue of guilt was determined on the basis of deeply flawed forensic evidence in circumstances where the applicant was denied procedural fairness in respect of a fundamental feature of the trial process concerned with disclosure by the prosecution of all relevant material," Justice Martin wrote.

However Justice Brian Martin said he was "fairly certain" Eastman was guilty but "a nagging doubt remains".

"While a strong circumstantial case remains, based on the admissible and properly tested evidence the case for the prosecution is not overwhelming; it is properly described as a strong circumstantial case," he wrote.

"There is also material pointing to an alternative hypothesis consistent with innocence, the strength of which is unknown."

Justice Martin recommended Eastman's conviction be quashed and said a retrial would not be feasible nor fair.

He also recommended Eastman be pardoned by the ACT executive.

"Regardless of my opinion as to the applicant's guilt, in my view the substantial miscarriage of justice suffered by the applicant should not be allowed to stand uncorrected," he said in the report.

"To allow such a miscarriage of justice to stand uncorrected would be contrary to the fundamental principles that guide the administration of justice in Australia and would bring the administration of justice into disrepute."

ACT Attorney-General Simon Corbell has welcomed the release of the report but says it is now up to the Supreme Court to determine what orders it should make as a result.

Eastman's lawyers are considering their next legal steps.

Australian Federal Police fail to delay report's publication

Justice Martin's report was delivered to the Supreme Court on Thursday and the court had planned to release it on Friday.

But counsel for the Australian Federal Police made an application to delay its publication because police adversely mentioned were yet to read it.

They also argued publication could reveal details of police operations against the Italian mafia.

But on Friday afternoon Chief Justice Helen Murrell ordered the report be released as soon as possible.

Eastman was convicted of shooting assistant commissioner Winchester after a trial in 1995.

He has mounted many challenges to that conviction but all have so far failed to secure his freedom.

But in this inquiry, the forensic case - which was key to his conviction - was discredited during evidence.

Eastman's lawyers called for inquiry head Justice Brian Martin to declare a miscarriage of justice and quash the conviction.

But lawyers for the police and the ACT Director of Public Prosecutions urged Justice Martin to find the circumstantial case against Eastman remains strong and the conviction should stand.