The lawyer for an innocent man whose arm was broken by police during a botched raid has described the police investigation into the incident as “an absolute joke”.

There are fears Nik Dimopoulos may lose the use of his left arm as a result of the injuries he sustained while being arrested by police in Fitzroy, in Melbourne’s inner-north, about 2am on Saturday.

When police broke into the garage of the building – which houses LGBT community bookshop and cafe Hares & Hyenas – Mr Dimopoulos ran from the property, fearing an anti-gay home invasion, according to a Facebook post by bookshop co-owners Rowland Thomson and Crusader Hillis.

Police were pursuing a suspect in a home invasion and carjacking case and believed an armed member of a ‘Lebanese’ gang was inside the property, according to the post.

Interviewed on ABC Radio Melbourne on Monday morning, Victoria Police Assistant Commissioner Luke Cornelius said the incident would be subject to an “independent investigation” by the force’s Professional Standards Command.

The lawyer for Mr Dimopoulos, Jeremy King, said it was “an absolute joke” to describe the force’s own investigation as independent.

Mr King said the investigation should be conducted by the Independent Broad-based Anti-corruption Commission, which should consider charges against the police officers involved.

“Victorians as a community have had enough,” Mr King said.

“Victorians don’t trust that Victoria Police will … look at it properly, and we really need to make sure that we have a strong IBAC who can step forward.”

Senior officer ‘appalled’ by injuries

Asked how Mr Dimopoulos had been so badly injured by officers during the arrest, Assistant Commissioner Cornelius said this was “a very good question”.

He said claims from eyewitnesses that the arresting officers had not identified themselves as police would form part of the investigation.

“From my perspective, it’s entirely understandable, that someone who believes they’re being the subject of a home invasion, and potentially a homophobic attack, it’s entirely understandable that an individual in that situation would be first and foremost focused on their safety, absolutely focused on trying to get away from that threat, and in those circumstances we know that in a dynamic situation, individuals may or may not hear what was said to them,” he said.

In a separate interview on Melbourne radio station 3AW, Assistant Commissioner Cornelius said he was “appalled” at the extent of Mr Dimopoulos’s injuries.

“I would be looking to express to Mr Dimopoulos in clear terms that I’m very sorry that what has happened to him has happened and that what has happened will be the subject of a thorough and independent investigation,” he said.

A Victorian parliamentary committee last year found the system for investigating police misconduct was “extraordinarily complex and confusing” and based on an “intricate, overlapping and sometimes fraying patchwork of laws, policies and processes”.

It called for a police corruption and misconduct division to be created within IBAC.