Jason Roberts, who has spent more than half his life in prison for the murders of two Victorian police officers, has had his convictions quashed by Victoria's highest court.
The Court of Appeal set aside Mr Roberts's convictions for the 1998 slaying of Sergeant Gary Silk and Senior Constable Rodney Miller on Tuesday.
"We are satisfied that a substantial miscarriage of justice has occurred," the Court of Appeal said.
"This is a case in which impropriety and unfairness permeated and affected the trial to an extent that it ceased to be a fair trial according to law."
A new trial has been ordered.
Mr Roberts's legal team told the court their client would apply for bail in the coming days.
Lawyer Simon Moodie, who is representing Mr Roberts, said his client welcomed the decision and looked forward to a fair trial.
The families of the two police officers released a statement saying they were "devastated" by the court's decision.
"It is not the decision we were hoping to hear, 22 long years after Gary and Rod were murdered," the families said.
"A number of lives changed when Gary and Rod were murdered, and lives will never be the same."
Wayne Gatt, from the Police Association of Victoria, paid tribute to the slain officers.
"This is a difficult day, one of too many to count for the families of Gary Silk and Rod Miller," Mr Gatt said.
"In 22 years, they've not been afforded the clear air and certainty to look forward without having to look back.
"Today, they learned that for some time yet, that will continue."
Court says there was a 'fundamental corruption of the trial process'
On August 16, 1998, Sergeant Silk and Senior Constable Miller were lying in wait for two unknown men who police believed were responsible for a series of armed robberies in Melbourne's south-east.
Shortly after midnight, they pulled over a car outside the Silky Emperor Restaurant on Cochranes Road in Moorabbin, when they were shot and killed.
After a four-and-a-half month trial, a jury convicted Mr Roberts and another man, Bandali Debs, over the murder of the two officers in 2002.
Mr Roberts, who was 17 at the time of the killings and must serve 35 years before he is eligible for parole, has always maintained his innocence.
He now admits he was committing the armed robberies.
Debs was sentenced to life in prison without parole, with the sentencing judge telling him: "Life means life."
A key piece of evidence used to convict the men was statements from police officers on the scene who heard Senior Constable Miller declare that two men were responsible for the shooting.
But in 2019, Victoria's Independent Broad-based Anti-corruption Commission uncovered that one of those statements, prepared by Senior Constable Glenn Pullin, was made months and not hours after the shooting.
The statement was backdated, and did not explain that Senior Constable Pullin was not listening carefully to what has become known as the 'dying declarations' of Senior Constable Miller, but was instead comforting him.
The discovery was significant because prosecutors relied on Senior Constable Pullin's evidence to back the suggestion there were two offenders, and corroborate other police accounts.
By 2005, Mr Roberts had already exhausted all his avenues for appeal, including in Australia's High Court.
But in 2019, Victoria's Parliament passed a new law which allowed a second appeal if there is fresh and compelling evidence, a provision which Roberts's lawyers seized on.
His appeal is the first of its kind under these news laws.
The Court of Appeal said there had been a "gross and fundamental corruption of the trial process".
"The appellant was confronting a trial of extraordinary gravity," the court said.
"A central plank of his defence was that the jury ought not be satisfied that there was more than one offender.
"After anxious consideration we have concluded that Pullin's undisclosed misconduct so corrupted the fairness of the appellant's trial as to poison its root."
