On a cold and wet winter's night in 2017, police arrived at a "very messy" one-bedroom apartment in Melbourne to find a dead man covered in a blanket with a knife in his hands.
Donald Brandenburg, 65, died from significant torso injuries, including a damaged liver which leaked two litres of blood into his abdomen.
Troy Simon Burns, 47, has pleaded not guilty to beating his "significantly older" flatmate to death on August 3, 2017, after a history of allegedly abusing Mr Brandenburg, hitting and dominating him.
Instead, Burns claims he acted in self-defence.
The Crown says Burns tampered with the crime scene at Ashwood and Mr Brandenburg's body, placing a knife in his dead hand, in order to "stage a self-defence scenario".
On Thursday, crown prosecutor Raymond Gibson QC said a few nights before Mr Brandenburg's death, Burns slapped him around the head after finding him in bed with his girlfriend, Song Cousland.
"I was going to chop his balls off that night, got the hedges out and everything," Mr Gibson said Burns texted to a friend.
"He's a creep, makes my skin crawl."
Then before his death, a neighbour heard Mr Brandenburg talking to himself, saying he was upset and that was going to "f***ing kill" someone.
After the alleged murder, Burns allegedly messaged friend Brandon West, saying: "I'm about to do 10 years jail".
"I've killed someone in self defence.
"He pulled a carving knife and held it to Song's throat so I hit him twice and he fell over the chair and hit his head on the floor.
"I'm too old to be going to jail for 10 years."
A post-mortem examination on August 4 showed Mr Brandenburg had suffered extensive internal bleeding, multiple broken bones, abrasions and blunt force trauma.
Burns' lawyer Richard Edney reminded the Supreme Court jury the three people who lived at the Ashwood unit had "significant issues" and lived "on the fringes of our society" with health, disability and drug problems.
He asked them to consider whether self-defence could be excluded beyond reasonable doubt.
Mr Brandenburg's sister Astrid gave evidence on Thursday, saying the trio had lived in a "tip".
She said her brother was scared of Burns, who would often take his bank card.
Mr Brandenburg's daughter Lisa Jane Gleeson said Burns had given her father a "few touch-ups" and had taken control of his bank cards.
She also said she didn't feel her father was capable of looking after himself.
Ildiko Runic, a regional assessment practice leader for the City of Monash, visited Mr Brandenburg a few days before his death and noted he was sleeping in the living room on some blankets.
"He started to tell us that he didn't feel safe, that Troy had a bad temper and he wanted to leave," she told the court.
She offered to take Mr Brandenburg away, but he refused, she said.
The trial continues on Friday.
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