An American tourist has told a jury a man accused of fatally bashing rocker Angry Anderson's son in a Sydney park showed "no emotion" as he "stomped on his head".
Mathew Flame, 22, is on trial in the NSW Supreme Court for the alleged murder of his close friend Liam Anderson after a night out in November 2018.
Trevor Buchert, who was holidaying in Australia, was on an early morning walk when he witnessed part of the attack in Pavilion Reserve at Queenscliff.
Mr Flame had taken up to 10 MDMA capsules in addition to smoking cannabis and drinking alcohol before he bashed Mr Anderson, the jury has heard.
Mr Buchert said the attacker "used the heel of his foot in a stomping motion" and stood on Mr Anderson's head.
"The blows were so severe, I thought they would be fatal," he said in his statement to police, which was read out in court.
"I called out, 'What are you doing?' (and) the male took one step back and started to look at me but did not say anything.
"The male's eyes were wide open with no expression on his face. He did not appear to be angry.
"I could see the victim turn his bloodied head towards me and he called out, 'Help me, help me, help me,' in a desperate manner as loud as he could."
Mr Buchert said he "sized up" but decided not to intervene because Mr Flame was bigger than him and didn't appear "coherent".
He called triple-0 and told the operator a man was "being murdered".
Nadia Khalil, who spent part of the night with the pair, said Mr Flame became "closed off" at her house.
She said he started to get flushed and hot, removing items of clothing and attempting to lie down before leaving the property.
Ms Khalil said she begged him to return.
"He wasn't saying anything, he would look at me as if he understood what I was saying but would not respond verbally," she said.
Mr Anderson also followed and tried to help Mr Flame.
The court heard the last thing Ms Khalil heard Mr Anderson say was: "He's my best friend, I would never leave my best friend."
Mr Flame has pleaded not guilty on mental health grounds and his defence team argues he had a severe psychiatric illness — schizophrenia — at the time.
The trial, before Justice Richard Button, continues.
