Jason Roberts will walk free from prison after nearly two decades for the murders of two Victoria Police officers after a fresh jury found him not guilty.

Sergeant Gary Silk and Senior Constable Rodney Miller were ambushed and killed in the early hours of August 16, 1998 while staking out armed robbery targets.

Bandali Debs is serving a life sentence for their murders.

Roberts, now 41, was convicted alongside Debs and jailed for a minimum 35 years in 2003.

But a fresh Supreme Court trial was ordered for Roberts after allegations of police wrongdoing were investigated by Victoria’s anti-corruption watchdog, IBAC.

After hearing months of evidence from dozens of witnesses, jurors returned their not guilty verdict on Monday.

They had been staying together at an undisclosed location to keep them away from outside influence while they made their decision, deliberating from Thursday and through the weekend.

Justice Stephen Kaye said the trial was one of the hardest he had seen a jury consider, given the length, COVID-19 complications, density of evidence and burden for each juror.

“This case has involved an enormous responsibility on each of your shoulders,” he said.

He gave the jurors a lifetime exemption from jury duty, but said he may waive it if any of them “have got a taste for the job”.

Roberts was escorted out the back of the court by police, pending his release from custody.

Three appeal judges found long-undisclosed conduct by one particular officer had corrupted Roberts’ initial trial.

Senior Constable Glen Pullin destroyed an original statement made about the murders and substituted it with a backdated document, containing dying declarations of Senior Constable Miller about there being a second offender.

He then lied about its existence in what the judges labelled a “gross and fundamental corruption of the trial process”.

Among the evidence jurors considered was that of Roberts himself, who confessed that when police came for him for the murders, he lied to protect himself.

He told them he knew nothing about the shooting murders and denied being involved in robberies with Debs.

“I knew what [Debs] had done and I didn’t want to be dragged into it,” he told jurors.

“I lied because Ben killed two police officers. That’s not a small thing.”

He said he got up during the night and saw Debs with a gun, listening to a police scanner.

Debs, he said, told him in detail about a “shootout” with the officers.

Roberts, who pleaded guilty to 10 armed robberies with Debs at the start of the trial, was 17 when he did the first robbery – getting involved while dating the four-time killer’s daughter Nicole.

Debs also gave evidence at the trial, claiming Roberts was with him at the Silky Emperor and fired the first fatal shot at Sergeant Silk when their car was pulled over in Moorabbin.

Debs, giving evidence from prison, rejected suggestions his evidence was designed to minimise his own role and was labelled a “vile and evil person, a psychopath and liar” by Roberts’ barrister David Hallowes.

Police colleagues also gave evidence, including Sergeant Helen Poke who said she won’t forget the words Senior Constable Miller uttered as she cradled his head in her lap: “Get them, I’m f—ed, two offenders, one on foot, six foot, dark hair, checked shirt, dark Hyundai”.

Sergeant Silk died at the scene, Senior Constable Miller died in hospital.

Following the verdict, Victoria Police Chief Commissioner Shane Patton said the officers’ deaths had an enormous impact on the police force.

“Our thoughts are with the Silk and Miller families today and we know this will be a difficult time for them,” he said in a statement.

“We will continue to support both families as well as the many police who continue to be impacted by the tragic loss.”

Victorian Police union secretary Wayne Gatt said the verdict was unexpected and would bring enormous grief to the policing community.

“Losing not one but two of our members at work some 24 years ago is the worst thing you could ever imagine,” he told reporters outside court.

“To have a day like today, some 24 years later, is probably just only second to that.”

Roberts will face a plea hearing over 10 armed robbery charges on September 8.

– AAP