A young man being sentenced over the murder of a teenager in Sydney's west has jumped from his seat in court and tried to attack his co-accused, shouting "you're dead, you f---ing dog!"
The youth, who cannot be named, was sitting in the jury box of the NSW Supreme Court on Thursday, having been deliberately separated from his co-accused, when he sprang up, leapt a metre-and-a-half to the ground and sprinted towards the dock.
He was restrained by security guards and a police officer just before he reached his fellow prisoner, 20-year-old Corey Loveridge.
Relatives of the victim in the case gasped as the youth grabbed a stapled wad of court papers and threw this at Loveridge.
"You're f---ing gone!" the youth shouted as he was swamped by court security and the detective in the case.
"You know what you f---ing did! I wanna run into you one f---ing day!"
Security staff and the detective were able to restrain the youth, handcuff him and return him to the jury box.
The youth and Loveridge, 20, are being sentenced over the December 2010 stabbing murder of a 17-year-old teenager at North St Mary's in Sydney's outer west.
Earlier this year, Loveridge was found guilty of murder in relation to the crime.
The youth pleaded guilty to murder before he could be tried.
Loveridge's murder trial heard that he and the youth, who were friends at the time, approached the victim, his older brother and stepbrother as they walked to a service station in the early hours of December 1, 2010.
The three brothers saw Loveridge, then 18, and the other man coming up behind them, calling out "what's the time?" before the stepbrother felt a "metallic object" swipe by his neck, the court heard.
The older brothers sprinted away, telling the victim to run.
They tried to get help but when they returned, the boy was face down in the gutter, the jury was told.
The boy died later in hospital, after suffering 30 wounds - most of them stab wounds - all over his body, including the chest, abdomen, heart, lungs, liver, neck and head.
Sentencing continued in the court once order was restored.
Sydney Morning Herald with AAP