Former Victoria Police boss Simon Overland was a driving force behind the use of 'Lawyer X' Nicola Gobbo as an informer, an ex-detective claims.
Former drug squad officer Paul Dale spent eight months behind bars charged with the murder of dealer Terence Hodson and his wife Christine, and says he was set up by Ms Gobbo. The charges were later dropped.
In a statement to Victoria's royal commission into police informers, Mr Dale said he thought conversations with Ms Gobbo, who he regularly socialised with, once slept with and occasionally received legal advice from, were protected by legal privilege.
But Mr Dale later discovered his conversations with Ms Gobbo had been secretly recorded by her and passed to police, in part corroborating statements made by underworld killer Carl Williams, linking him to double murders.
Williams' murder led to the charges being dropped, but not before a court hearing in which Mr Dale said it became clear Ms Gobbo was helping police.
"It was during my committal it became apparent that Nicola was a police informer and was turned into a prosecution witness on the instructions of the then-chief commissioner, Simon Overland, in an attempt to convict me of charges I had not committed," he told the commission in a statement released on Tuesday.
He said another officer, then-detective senior sergeant Boris Buick, told him after he was acquitted of perjury charges that Mr Overland had pushed for the use of Ms Gobbo as an informer.
"I spoke to Boris who made it very clear to me that he did not agree with using Ms Gobbo as an informer/witness but was directed to do so by Simon Overland," Mr Dale revealed.
He said Ms Gobbo's informing was a fundamental breach of her duties as a lawyer.
"I spent eight months in custody in the most onerous conditions within the Acacia Unit, Barwon Prison as a direct result of Nicola Gobbo's and Victoria Police's atrocious and unethical actions and what I believe to be criminal behaviour," he said.
Ms Gobbo was first registered as an informer in 1997, again in 2000 and for a third time between 2005 and 2009.
Mr Overland ordered police stop using information from her in mid-2010.
The commission is set to hear more evidence from Mr Dale later this week, but on Tuesday re-called his one-time close friend, Detective Senior Sergeant Tim Argall.
He contacted Ms Gobbo when Mr Dale was arrested over an Oakleigh drug house burglary involving Hodson and Mr Dale's drug squad colleague David Miechel, who subsequently spent 12 years in prison for his part.
Sen Sgt Argall agreed Mr Dale had been paranoid and was "bothered" that Hodson would implicate him.
They both received legal advice from Ms Gobbo at that time - Mr Dale about the burglary and Sen Sgt Argall about his association with Mr Dale. Burglary charges against Mr Dale were dropped when the Hodsons were killed.
Sen Sgt Argall stopped speaking to Mr Dale after police instituted an association policy, requiring him to officially declare their friendship.
Australian Associated Press