Disturbing CCTV footage shows the moment Matthew Newton struck a Miami hotel worker in an apparent dispute over a dropped phone call.
Newton was been arrested and charged over the alleged battery of the employee, and with resisting arrest in Miami.
It's claimed Newton went to the front desk at 4.50am to complain after about a dropped phone call, before throwing papers around the lobby and striking the worker 'with a closed fist'.
CCTV footage clearly shows the hotel worker standing with his hands behind his back before Newton strikes him in the head.
Disturbing footage moments later shows the worker lying on the floor, with Newton lying beside him, before appearing to check on the worker's condition.
Newton has reportedly claimed he was spat on by the hotel worker.
Newton's high profile Sydney lawyer Chris Murphy has tweeted in defence of his client.
"Can't cure mental illness with 'You stop that!'.Bipolar sufferers need patience & support.Matthew Newton has mine.Treatment continues", he tweeted this morning.
Newton is on bail in Miami after being charged two weeks ago following an incident involving police at a local bar.
The incidents in the US follow a number of run-ins with the law at home.
Newton's father Bert is confident his son will get through his troubles.
Speaking from his Melbourne home this morning, Bert said his family remains strong and positive.
"We're pretty positive people, we'd like this to have a happy ending and I'm sure it's still possible," he told 7News.
"We're doing everything we can to try and help that happy ending."
Newton is currently facing charges over the alleged assault of a Sydney cab driver.
He has previously faced charges of assaulting his former girlfriend, actress Brooke Satchwell.