Systems to deal with police brutality in Northern Ireland and New York should be considered for adoption in Victoria, legal experts say, after a doctor joined a growing list of alleged victims of excessive force in the state.

Key points: In Victoria, IBAC can investigate complaints about police, but most complaints are investigated by the force itself

In Victoria, IBAC can investigate complaints about police, but most complaints are investigated by the force itself Under complaints systems in New York and Northern Ireland, experienced investigators from outside the force examine complaints against officers

Under complaints systems in New York and Northern Ireland, experienced investigators from outside the force examine complaints against officers Acting Premier Jacinta Allan has defended the existing arrangements and says the roll-out of body-worn cameras will increase police accountability

An investigation by 7.30 and The Age this week aired allegations from Melbourne doctor Kim Proudlove that police assaulted her after she sought to help a barely conscious and bleeding man who was surrounded by officers in April 2018 — and that they then covered up the brutality.

On Monday, the investigation revealed a Victorian policeman retained his job and rank despite being caught on CCTV assaulting a drunk disability pensioner at Geelong Police Station.

It also reported the case of Aboriginal teenager Tommy Lovett, who was wrongly arrested and allegedly subjected to police brutality in April 2016.

The incident involving Dr Proudlove occurred just 19 days after 7.30 and The Age revealed explosive CCTV vision of police allegedly assaulting a Melbourne disability pensioner during a mental health welfare check.

Dr Kim Proudlove's injured lip. ( Supplied )

A state parliamentary committee found in September the current system for handling police complaints was "extremely complex … based on an intricate, overlapping and sometimes fraying patchwork of laws, policies and processes" involving Victoria Police and the Independent Broad-based Anti-corruption Commission (IBAC).

IBAC handles just 2 per cent of police complaints, sending 98 per cent back to the police.

The state parliamentary committee said the proportion of complaints IBAC investigated was "insufficient".

Colleen Lewis, an associate professor in the criminology department at Monash University told ABC Radio Melbourne it was problematic for any profession to investigate their own.

"It's appalling", Dr Lewis said.

"Police cannot investigate police — but it has been going on since the 60s."

Kim Proudlove alleges she was assaulted by police. ( ABC News )

"Police are the coercive arm of the state.

"They have incredible powers — they can deprive you of your liberty, they can legitimately take your life.

"We're not talking about your average public servants here. We need a much better way in which to deal with complaints against police. "

The Police Accountability Project — run by the Flemington and Kensington Community Legal Centre — supports an independent investigative body to look at police complaints.

"At the moment, it's incredibly opaque what happens in that process," the centre's executive officer Anthony Kelly said.

Mr Kelly says just 2 per cent of assault complaints are upheld, while 8 per cent of general complaints are substantiated.

International experience of independent agencies shows a different story.

Calls to borrow from overseas oversight models

The likes of the Civilian Complaint Review Board in New York and the Police Ombudsman of Northern Ireland are independent of police, and substantiate between 23 and 24 per cent of complaints, according to Mr Kelly.

Mr Kelly said those agencies had the resources and the ability to be on site immediately after a complaint is made, gathering evidence and interviewing affected officers.

Since 2000, the Police Ombudsman of Northern Ireland has investigated current and historical complaints against police.

It has 120 dedicated investigators who decide whether police officers have acted properly, according to its website.

Investigators consider witness statements, police radio transmissions, forensic evidence and other material.

The office promises to "treat complainants and police officers fairly and equally".

It does not employ former police from Northern Ireland, but it does second staff from other police forces.

Aboriginal teenager Tommy Lovett was wrongly arrested by police and allegedly assaulted in April 2016. ( Supplied )

The Civilian Complaint Review Board was set up in New York City in 1993.

It is staffed by civilians and, according to its website, investigates four types of police misconduct — excessive force, abuse of power, discourtesy and offensive language.

The process is overseen by seasoned investigators from other agencies, like the NYC Transit Police or former prisons staff.

Detailed statements are taken from the complainant as well as the officer who is the subject of the complaint.

Investigators might also look at medical records, CCTV and speak to other witnesses.

"They gather evidence more effectively," Mr Kelly said.

"It makes for a much more robust institution."

Victoria Police says the existing oversight model is "the most appropriate and effective". ( ABC News: Stephanie Anderson )

An IBAC audit in March last year revealed serious flaws in the way police were handling complaints, highlighting concerns about conflicts of interest, failure to address human rights issues, and inadequate supervision by managers.

In September, it appointed a new deputy commissioner, Katie Miller, to take a special interest in IBAC's oversight of police.

"Building public trust can be a challenge for integrity agencies: their work can be very technical, and due to its confidential nature can sometimes portray a sense of secrecy," Ms Miller said in a statement at the time.

In February 2018, Brett Guerin stepped down from his role as head of the police standards command, which oversees internal investigations, after being found to have made racist and sexist remarks on social media.

Police officer Michael Cooke pleaded guilty to assaulting disability pensioner Phil Dickson. ( Supplied )

Existing model 'appropriate and effective': Victoria Police

In a statement responding to the media investigation, Victoria Police said it believed the existing oversight model was "the most appropriate and effective".

"We cannot outsource our integrity," it said.

"We believe our current model not only strikes the right balance between police retaining accountability and responsibility for addressing poor performance and misconduct, it also facilitates effective oversight and scrutiny through an independent body."

Dr Lewis said the response from police command was predictable.

"I have heard it so many times before," she said.

"We cannot just keep replaying the same record. We need change."

Acting Premier Jacinta Allan defended the existing oversight arrangements this week, and said the roll-out of body-worn cameras would increase accountability for officers.

"We have the very highest expectations of professional standards from Victoria Police, and overwhelmingly Victoria Police do a very strong job in supporting our Victorian community," she said.

"Where there are incidences of behaviour that's not acceptable, IBAC has the capacity to take on and investigate these matters."