A Victorian police officer filmed appearing to stomp on a mentally ill man's head during an arrest is under criminal investigation by the state's corruption watchdog.
The senior constable was suspended with pay after footage shared on social media showed him appearing to kick Timothy Atkins' head while the man was on the ground.
Video also showed a police car speeding up and hitting the 32-year-old, who has bipolar, before his arrest at Epping, in Melbourne's north, on Sunday.
Mr Atkins' family says the "hardworking, family-orientated man" has been left in an induced coma.
Deputy Commissioner Neil Paterson labelled the Critical Incident Response Team officer's use of force as inappropriate and the car footage concerning.
"When you look at that footage and you see a police vehicle hit a person and he's knocked forward up in the air and hits the ground, it looks concerning," Mr Paterson said.
The Independent Broad-based Anti-corruption Commission has taken over a criminal investigation into the suspended police officer. He has not been charged.
Another officer, who was behind the wheel of the police car, has had their driving privileges revoked.
Mr Atkins went to the Northern Hospital Epping for mental health treatment at 9pm on Saturday.
He was still waiting at 4pm the next day when he smashed the hospital's glass doors and police were called, the deputy commissioner said.
He described the man running among traffic, kicking a police car and hopping on its bonnet before being hit by the vehicle and tackled to the ground.
"We've got a man that's shown quite excessive violence at the hospital, smashed two large glass doors, taken them off their hinges and exited the hospital," Mr Paterson said.
"The police up there describe a situation where they thought this man will carjack a vehicle."
He added Mr Atkins was likely to be charged.
The man's father, Glenn, had called for the officer who kicked his son's head to be sacked.
He said his son had gone to the Northern Hospital Epping before running outside to meet a work colleague, which prompted hospital staff to call the police.
The family have set up a GoFundMe appeal for his treatment.
Premier Daniel Andrews denied Victoria Police had a serious cultural problem, and said it was appropriate the officer had been stood down.
Opposition Leader Michael O'Brien raised concerns about what he said were increasingly aggressive tactics from police during the COVID-19 pandemic.
"Particularly that fellow who hadn't committed a criminal offence but was having a mental health episode," Mr O'Brien said.
"That fact that this fellow was apparently knocked down by a car and then had his head stomped on, that's not the sort of thing that should happen to any Victorian."
Australian Associated Press