Charlie Bezzina led the investigation into the 2004 Melbourne murder of Mr Hodson and his wife Christine, for which drug squad detective Paul Dale was a prime suspect.

But Mr Bezzina told Victoria's royal commission into police use of informers that he wasn't given all the information he needed, including that barrister-turned-informer Nicola Gobbo was in a sexual relationship with Mr Dale.

He was required to give senior officers including Simon Overland, who went on to become chief commissioner, weekly updates on the case.

"Things I've learned, in hindsight I've formed the view Overland was running his own investigation behind my back," Mr Bezzina said.

He described it as a "bit of a cluster" by the Ethical Standards Division and said he "had words" with the department on the night the informer and his wife were killed.

"I was annoyed as to the fact - why did they leave Hodson to his own devices," he said of the man informing on Dale over corruption allegations.

"He didn't want to go into witness protection, but they let him set up his own surveillance - that was a big issue for me."

Mr Bezzina suggested it might have been that police had no money to provide Hodson with home security surveillance.

"But to me, that was incompetent. I felt that I was left scrambling," Mr Bezzina said.

He said he wasn't told about any intimate relationship between Ms Gobbo and Mr Dale, or about recorded conversations between the pair and crime boss Carl Williams.

Williams told police he arranged hitman Rodney Collins to kill the Hodsons at Mr Dale's request.

Charges against Dale and Collins were dropped when Williams was murdered in prison in 2010.

Mr Bezzina interviewed Ms Gobbo after the Hodson killings, saying it was in part to see if she'd encourage her client Tony Mokbel to speak to detectives.

The commission also heard on Tuesday that Ms Gobbo's informing included claims Mokbel, currently serving 30 years in prison for drug trafficking, had tried to bribe a police officer with $2 million to destroy tapes containing evidence against him.

Retired superintendent Terry Purton worked with the ESD and later investigated complaints and corruption within Victoria Police, including a review of alleged drug squad corruption which prompted changes to police informer handling practices.

"There were major, catastrophic issues in relation to informer management. People did their own thing. It was a mess," he said.

Mr Purton revealed he'd heard scuttlebutt about Ms Gobbo's relationships with fellow lawyers and that she had "tried to drag some (police) members into bed".

"It was strictly controlled but coppers still talk ... because of her behaviour in the media, allegations of sexual relationships with police, allegations other having sexual relations with crooks," he said.

He was aware of information said to have been provided by Ms Gobbo, having sat in on meetings with senior officers through 2005.

Mr Purton said while use of a barrister as a source was unethical, police had used whatever means they could to end the bloodshed during the gangland wars.

Australian Associated Press