Jason Roberts refused bail as he awaits fresh trial for police murders

Accused cop killer Jason Roberts has been denied bail after his murder conviction for the deaths of Sargent Gary Silk and Senior Constable Rod Miller in 1998.

Mr Roberts applied to be released from Barwon Prison this morning to prepare for his re-trial after the Court of Appeal deemed his original trial "poisoned to the roots" just two weeks ago.

But Justice David Beach did not let him walk - despite Roberts putting up a $500,000 surety.

He said if Roberts was found guilty a second time, only a small amount of his likely sentence will have been served.

"He will have served only a fraction of the sentence likely to be imposed."

He has been in prison for more than 20 years for the murders, spending more than half his life behind bars.

Sgt Miller and Snr Constable Silk were killed on duty after being shot in the early hours of August 16 in 1998, while investigating a series of robberies outside the Silky Emperor restaurant in Moorabbin.

Roberts and co-accused Bandali Debs were convicted by a jury of the murders four years later.

Despite admitting his role in at least 10 armed robberies alongside Debs, Roberts has always maintained he wasn't there that night.

The decision of a retrial follows an appeal in June this year, where Roberts' barrister, Peter Matthews, said police had deliberately manipulated and concealed evidence about the number of offenders at the scene, which was central to the prosecution case.

Roberts' legal team argued the 40-year-old should be freed on bail to prepare for what they dubbed the "trial of his life".

They said Roberts had already endured significant personal hardship in custody.

The new trial is not set to commence until at least the end of next year.

He is expected to give evidence of an alibi at his fresh trial, with his defence lawyer Peter Matthews arguing "two guns doesn't necessarily mean two shooters".