It was considered “career limiting” within Victoria Police to talk about the death risk faced by informer lawyer Nicola Gobbo.

Towards the end of the barrister’s lengthy shadow career of informing on her own clients, senior officer Tony Biggin became increasingly concerned Ms Gobbo would end up dead and related convictions could be quashed.

But voicing these fears within the upper echelons of Victoria Police in late 2008 and early 2009 was considered something that could hurt your career, Mr Biggin told Victoria’s royal commission into the use of police informers on Thursday.

His concerns stemmed from a push to make Ms Gobbo a witness in covert murder investigations, linked to Melbourne’s bloody gangland era.

Mr Biggin spelled out how making Ms Gobbo a witness in the investigation against ex-detective Paul Dale risked revealing the lawyer as an informer, put her life at risk and jeopardised previous criminal convictions.

“So if it all went completely pear-shaped there would be a record of not just conversations that had happened but a physical record of what your views were?” counsel assisting the commission, Andrew Woods, asked Mr Biggin.

“Correct. And let me say these are career-limiting papers that are sent,” the former officer replied.

He explained that passing handlers’ concerns about making Ms Gobbo a witness to the force’s hierarchy could stymie promotion opportunities.

“I was concerned for them that by standing up to the organisation and saying, ‘We think you’re making the wrong decision in this’, for them, their careers may well have a black mark against them, at least in the short term,” Mr Biggin said.

While conceding he had general concerns about previous criminal convictions being in jeopardy, the one-time drug squad boss denied holding fears about any specific case related to Ms Gobbo’s informing.

“But you did know that there was a risk of convictions that had been made being found to be unsafe, so you knew there were some convictions?” Mr Woods asked.

“That’s always a possibility, yes,” Mr Biggin replied.

Ms Gobbo was deregistered as a source in 2009 so she could be a witness in the prosecution case against former detective Paul Dale.

He was charged with the 2004 murders of police informers Terence and Christine Hodson five years prior.

But the allegations were later dropped after the prison murder of underworld killer Carl Williams, who had implicated the former detective in the Hodson killings.

Gobbo worked with police on-and-off between 1995 and 2009, but continued to unofficially give them information until 2010.

She went on to sue former police commissioners Christine Nixon and Simon Overland that year for allegedly failing to protect her.

In July this year Faruk Orman’s criminal convictions linking him to the killing of underworld figure Victor Peirce, and subsequent jail sentence, were quashed after a court found a “substantial miscarriage of justice” because of Ms Gobbo’s involvement.

-AAP