Detective Senior Sergeant Tim Argall told a royal commission on Monday he also later sought legal advice from Ms Gobbo when a friend of his - drug squad detective Paul Dale - was charged with the burglary of a drug house in Oakleigh.

Senior Sergeant Argall said he socialised with her in later years when she was not informing to him, after regularly seeing her at court when she was a barrister and he was working as a detective.

"There was an occasion in about 1997 where you had an episode of physical intimacy with her, if we can put it that way," counsel assisting, Chris Winneke QC, said.

"Yes ... I don't think it was after court. There was probably some other contact or arrangement to catch up and it eventuated from that," Senior Sergeant Argall responded.

The public inquiry is investigating the actions of Ms Gobbo, who gave police information on some of the state's most notorious underworld figures, and Victoria Police, who first registered her as a source in 1995.

The scandal has called into question the convictions of a number of notorious gangland figures, many of whom she represented, because of suspicions the information could have been protected by lawyer-client privilege.

On Monday the inquiry was also told Commander Brett Curran, who is Police Chief Commissioner Graham Ashton's chief of staff and was chief of staff to Premier Daniel Andrews when he was in opposition, was in charge of the asset recovery squad crew who registered Ms Gobbo in the second instance in 1999.

She had been earlier been registered as informer G3/95 in 1995 after she gave police information that her boyfriend was dealing guns. She tried to set him up in a failed undercover sting called Operation Scorn, the commission heard.

"She was eager to participate," Senior Sergeant Argall said.

"She was, yeah, when it came to using the covert operative, she was excited about that."

Senior Sergeant Argall said Ms Gobbo rang him for help a year later, in 1996, to get rid of a media scrum outside the Gobbo family home in Kew.

The media were chasing her after she was embroiled in a political hoax when she publicly claimed a Liberal politician forged letters to damage the Keating Labor government ahead of the 1996 federal election.

"'What do you want me to do Nicola?' I'd expect that was my initial reaction," Senior Sergeant Argall said.

"[But] she's somebody that's provided information to police, if there's something in our ability to help her, I'm happy to see what we can do."

Senior Sergeant Argall met her in Melbourne Central, a crowded shopping centre, to help her shake the media tail.

He told the commission he later invited Ms Gobbo to a homicide squad function and she, like many lawyers, regularly attended them.

He said he went over to her house in Port Melbourne after work one night and saw her socially every month.

She also socialised with Paul Dale, Senior Sergeant Argall said, who he was friends with when they worked together at Brunswick police station.

Dale was charged with a burglary on a drug house that was the target of a surveillance operation by his squad in 2003.

Senior Sergeant Argall said he sought legal advice from Ms Gobbo. Senior Sergeant Argall said he sought legal advice from Ms Gobbo. One occasion, he met Ms Gobbo with Dale.

"I had an association with Paul Dale at the time, and I just wanted some advice on my association with Paul," he said.

Victoria Police did not tell the commission Ms Gobbo was registered in 1999 and 1995 until several weeks after the commission was announced in December last year. It was initially focused on her registration from 2005-2009.

Detective Senior Constable Jeff Pope registered Ms Gobbo in 1999 after she alleged a fellow lawyer was laundering money and fraudulently obtaining Legal Aid funds, the inquiry heard.

Mr Pope told the inquiry he was introduced to Ms Gobbo by drug squad detective Wayne Strawhorn, who was jailed in 2006 for drug trafficking.

Mr Pope said he briefed Mr Curran and a fraud squad solicitor before he registered her.

Mr Pope, now retired, became an assistant commissioner and was on a steering committee that reviewed the source unit that handled Ms Gobbo in the gangland years before the unit was disbanded. He faces further questioning on Tuesday.

- The Age