Flashback: The day David Eastman was released from prison after conviction quashed

David Eastman is a free man, released on bail after his conviction for murdering ACT police chief Colin Winchester was quashed.

After serving more than 19 years of a life sentence, he was driven out of the Alexander Maconochie Centre about 6pm, covered with a blanket in the back of a maroon sedan. It is not known where Eastman will be taken or whether the government will provide housing, however, ACT Attorney-General Simon Corbell said he would receive all the assistance normally given to released prisoners and he would not go homeless.

Despite his newfound freedom, the prospect of a retrial for the 1989 murder of Commissioner will hang over Eastman's head.

ACT Director of Public Prosecutions Jon White issued a statement on Friday afternoon saying the new trial was under consideration.

Meanwhile, ACT Victims of Crime Commissioner John Hinchey spoke on behalf of the Winchester family, saying they were up for a retrial.

"The Winchester family remain steadfast and resolute in their pursuit of justice for Colin Winchester and would support any retrial of David Eastman," he said.

The ACT Supreme Court on Friday ordered Eastman face a new trial over the assassination.

The spotlight is now on the Director of Public Prosecutions, who has the ultimate say over whether Eastman will be hauled back before court for a second trial.

Eastman was released from the Alexander Maconochie Centre after agreeing to abide by bail conditions. The conditions include that he not approach a list of more than 200 people, including the Winchester family. He will also need to give authorities at least 48 hours notice if he intends to leave the ACT.

He will return to court on September 11, although a new trial - if it goes ahead - will not happen until at least 2015.

In a judgment published on Friday, the court, comprised of Justices Steven Rares, Michael Wigney and acting Justice Dennis Cowdroy, found Eastman did not receive a trial according to law.

The judges said a fair trial was a fundamental right of every person charged with a criminal offence.

"It would be an affront to justice to permit the conviction to stand. We have concluded that the conviction be quashed," Justice Rares said.

The judges said a new trial had been necessary as a strong circumstantial case of murder of a senior police officer existed against Eastman.

The court heard he should not "escape having a jury decide whether or not he is guilty of that crime".

"Weighing all the relevant factors and considerations, we have concluded that the interests of justice require that we order a retrial," Justice Rares told the court.

A retrial was thought by many to be an impossibility as witnesses are dead, forensic evidence has been destroyed, and finding a jury free from the taint of prejudice after so many years of media coverage would be difficult at best.

Eastman's lawyers say trying to defend the case decades down the track would put him at a severe disadvantage.

But the court on Friday said it had not been convinced that a new trial would be unfair.

"We are satisfied that an order for a new trial would not deprive Mr Eastman of the capacity to protect his position ... there was no evidence of any damage from publicity to Mr Eastman's position before us and any retrial would not occur immediately," Justice Rares told the court.

"Whether the director decides to present Mr Eastman for trial again will be a matter for the exercise of his prosecutorial discretion.

"If that occurs, it will be open to Mr Eastman to make any application for a stay to the trial judge."

The ACT DPP has previously argued that an overwhelming case still points toward Eastman's guilt.

They say the evidence shows he had a clear motive, was linked to the murder weapon, was seen casing out the scene prior to the killing, and was unable to explain his whereabouts the next day.

Prosecutors say there is still evidence that Eastman made threats against Mr Winchester and uttered confessional-type statements, picked up on police bugs placed in his home.

Whatever comes next, this momentous decision closes a long-running chapter in the interminable Eastman saga.

It also means another of Australia's most infamous criminal convictions has fallen over because of shoddy forensic work.

The gunshot residue analysis, so critical in proving Eastman's guilt in 1995, was completely discredited in an inquiry into the former Treasury official's conviction, presided over by former Northern Territory Chief Justice Brian Martin.

Earlier this year, Acting Justice Martin found a "substantial miscarriage of justice" had occurred and called for Eastman's conviction to be quashed.

Eastman will be freed in the face of a finding by Acting Justice Martin that he is fairly certain of his guilt, but holds a "nagging doubt".

The inquiry's recommendations came before a full bench of the ACT Supreme Court, who ultimately held Eastman's fate in their hands.

Prosecutors last month made a last-ditch attempt to convince the court to keep Eastman behind bars.

But, as a packed courtroom watched on, the three Supreme Court judges ruled in the prisoner's favour on Friday afternoon.

Experts have said Eastman may struggle to re-adjust to life outside, after spending so long in the highly-regimented and controlled environment of a prison.

He may eventually get a shot at compensation for wrongful imprisonment, which some lawyers have estimated could reach into the millions.

He was convicted on a circumstantial case, to which the forensic evidence was central.

Victorian-based expert Robert Collins Barnes strongly linked gunshot residue found in Eastman's Mazda boot with the murder scene.

Even Eastman's trial judge, Ken Carruthers, paid tribute to the strength of the forensics when sentencing Eastman to life in November 1995.

"This investigation must surely rank as one of the most skilled, sophisticated and determined forensic investigations in the history of criminal investigation in Australia," he said at the time.

That statement was left in tatters by the Eastman inquiry.

A covert recording between the supposedly-independent Mr Barnes and a senior detective was played to the inquiry in which he described himself as a "police witness", and attempted to stymy attempts to have his work thoroughly reviewed.

Any serious investigation of Mr Barnes would have found he lacked objectivity, overplayed the strength of his evidence, and became emotionally involved in the case, the inquiry found.

The provenance of critical evidence was either non-existent or highly doubtful, and fundamental data was not produced by Mr Barnes prior to trial.

"In some instances it is apparent that Mr Barnes could not have undertaken the organic analyses upon which he claimed to have based his opinions," Acting Justice Martin found.

"In other respects, the contemporaneous accounts strongly suggest that such analyses were not carried out and that Mr Barnes' report was wrong."