Bradley Dusan Fletcher, 39, is standing trial for the murder of 32-year-old Bradley Evennett on March 22, 2024, when they sparred with boxing gloves on as they celebrated moving into a sharehouse together.
Fletcher's then-girlfriend Jasmine Robinson, who was also due to move into the Melonba house in Sydney's northwest, told a NSW Supreme Court trial on Monday she was "best friends" with Mr Evennett, who she knew by the nickname "B-rad".
Ms Robinson said the men spent the afternoon drinking and doing "boy stuff" and appeared to be having fun with each other.
"The boys started having a few beers and we were all in good spirits," Ms Robinson said.
"They were out the back being hoons. Just mucking around like children."
Ms Robinson left the house to attend to some other matters when she received a call from Fletcher, she told the court.
Fletcher said Mr Evennett had fallen over and she needed to come back, but soon called again and said he had stopped breathing and she needed to hurry, Ms Robinson said.
When she arrived back at the house, Ms Robinson said she saw a large amount of blood and Mr Evennett lying face down on the grass in the backyard with Fletcher pacing up and down.
"I've said, 'what the f***, what the f***'s going on here, why have you done this?" Ms Robinson said.
"He's charged over towards me. He's like 'I had to. He doesn't care about your safety, you don't understand'."
Fletcher allegedly went to pick Mr Evennett up which Ms Robinson said caused her to scream to put him down.
"That's when he came at me and said "shut the f*** up, I'm going to kill you too'," she said.
Fletcher then began making phone calls which Ms Robinson said she used as an opportunity to leave.
As she was leaving, Fletcher asked her "look at my eyes, do they look evil to you now?", Ms Robinson told the court.
Some time later Ms Robinson said she went to Mount Druitt police station.
Mr Evennett's body was found dumped on a footpath with a head injury, brain bleeding, broken eye and facial bones, broken teeth - including a molar found in his airways - rib fractures, and abrasions on his limbs and neck.
Fletcher pleaded not guilty to murder, claiming Mr Evennett's death occurred by accident during their sparring session.
The now 39-year-old pleaded guilty to manslaughter, however the lesser plea was rejected by prosecutors.
The trial continues.