“Does that represent his beliefs? That’s the sort of stuff I’m trying to understand.”

Flemington Kensington Community Legal Centre called for not only a review of the complaints handled by Mr Guerin when he was the head of Professional Standards Command, but for IBAC to expand its investigation into how he was promoted through the force.

“Police officers holding known racist views, supported through the ranks through senior command and placed in critical positions where they have to make ethical decisions and supervise complaints. It speaks to the ability of Victoria Police to own its integrity process,” Mr Kelly said.

“Without a thorough review of the entire process that Brett Guerin has gone through in terms of his promotion, his complaint history, his conduct oversighting complaints over race discrimination, homophobia and transphobia...We can’t be satisfied Victoria Police has the integrity to adequately assess complaints.”

A parliamentary inquiry into the oversight of police corruption and misconduct began its public hearings last week.

The inquiry has heard submissions from human rights groups who are calling for an increase in IBAC resources so it can properly investigate misconduct complaints or, better yet, a new body such as those in Northern Ireland and Canada that handles misconduct rather than criminal matters.

The inquiry was told most complaints to IBAC, about 90 per cent, were handed back to police for investigation.

Such was the case with Mr Guerin, who was initially referred to IBAC last May before the watchdog passed the complaint back to police after “careful assessment”.

The initial complaint was made by the Community Advocacy Alliance, a group of former senior police officers who have been critical of the force's direction, after Mr Guerin criticised group chair Kel Glare on its Facebook page for being “out of date”.

Under the Act, an assistant commissioner who is the subject of a complaint must be referred to IBAC. It is within IBAC’s powers to investigate police conduct that could bring force into disrepute.

The first set of Mr Guerin's remarks were considered by Mr Ashton and IBAC to be low-level, but the unfolding saga calls into question just what, if any, investigation was done into Mr Guerin’s online history after the first complaint.

It took basic searches by The Age in the past week to uncover some of the more serious misconduct under the pseudonym Vernon Demerest, which was used to conceal Mr Guerin's identity.

When asked how Mr Guerin's online behaviour was not discovered by an IBAC investigation last year, Police Minister Lisa Neville admitted the probe didn't delve deeply enough.

"I know there was a matter that police chief commissioner referred to IBAC [about Mr Guerin] and IBAC at that point said they didn't even think there needed to be any disciplinary action. They didn't obviously look more deeply at some of the history involved here," she told 3AW on Tuesday afternoon.

Ms Neville conceded the saga had been "embarrassing" for the police force and IBAC.

"He was a member for 40 years in the police force, it wasn't like he has just come off the streets and we're doing reference checks," she said. "He was a senior member of Victoria Police... it's almost like he had two separate lives. A lot of people are very shocked by discovering all of this about Mr Guerin in the last few days."

Mr Ashton said staff from his office were carrying out online searches to try to gauge Mr Guerin's posting history and they would’ve “ended up down the same path” as the media.

He was only aware, he said, of the “more serious behaviour”, which resulted in Mr Guerin being referred to IBAC for the second time, recently.

“We have taken action here and we have demonstrated it’s unacceptable,” he said.

Mr Ashton also defended the status quo, saying IBAC already oversees the complaints process and he was loath to outsource the force’s integrity.

“I expect managers to lead and to manage integrity in their units... integrity needs to form part of the ongoing conversation at all times with police. It’s part of the core responsibilities of police,” he said.

Mr Ashton acknowledged the saga could damage the force’s relationship with minority communities and upset its work in overhauling Victoria Police's culture through tackling issues of sexual harassment and homophobia within the force.

Ahmed Hassan is on police's taskforce of African community leaders. The 21-year-old with Somali heritage said the racist remarks allegedly made by Mr Guerin were hurtful and damaging.

"It made me want to lose hope," he said.

"But an individual doesn't represent a whole organisation. Knowing the Chief and knowing Deputy Commissioner Andrew Crisp, this is not what they represent. This is not their views."

For now, the police officer who has led that cultural change - Assistant Commissioner Luke Cornelius - will fill-in as head of professional standards while command searches for a permanent replacement.