The sister of accused murderer Aleksander Vojneski has broken down while remembering a family barbecue at which her brother calmly walked up to her boyfriend and stabbed him in the chest.
Vojneski, 31, faced the second day of his murder trial in the ACT Supreme Court on Tuesday, watching as his sister gave evidence about his past.
He is accused of stabbing his girlfriend, Paula Conlon, 30, to death in the bedroom of her Macgregor home late one night in March 2012.
The Crown allege Vojneski - who had a history of mental health problems, drug abuse and violence - was drinking, had no money and was becoming increasingly frustrated by failed attempts to get drugs on credit.
At the time, prosecutors say Ms Conlon believed she was pregnant and was trying to get her boyfriend to stop taking drugs. She had also spent the last of her money on clothes, the receipt for which was found ripped up in her kitchen sink after the murder.
Those circumstances were like a "pressure cooker" for Vojneski, the Crown allege.
There were no direct witnesses to the killing, but a teenage boy was in the house playing an online computer game with headphones on in another room of the house.
As part of the circumstantial case against Vojneski, Crown prosecutor Shane Drumgold is leading evidence of his alleged violent tendencies.
Vojneski's sister gave evidence at the trial on Tuesday, recalling an incident involving her then boyfriend at a family barbecue a decade before Ms Conlon's murder.
She remembered standing in kitchen at her parents' Canberra home, when Vojneski opened a drawer and picked up a knife.
Her brother was said to have walked straight up to her boyfriend, calmly, and stabbed him in the chest.
"[It was] very calm, very quiet, no screaming or shouting," she said.
Vojneski and her then boyfriend had been involved in a violent incident in the past.
They had been speaking about the previous violence earlier, she recalled, with her brother telling him there were "no hard feelings".
Despite her brother's words, she said she felt he was trying to instigate something with her boyfriend at the barbecue.
In cross-examination, barrister Jack Pappas asked her about a statement to police, in which she had described the knife as a pocket knife.
He also quizzed her about whether her boyfriend was being violent towards her in the lead-up to the stabbing.
Mr Pappas asked her whether Vojneski had argued with her boyfriend about his violence towards her on the day of the barbecue.
She said she didn't remember any such argument.
The trial continues before Justice John Burns.