A teenager who helped lure a boy to a suburban home and took part in the prolonged assault that killed him has been jailed for at least a decade.
He was among a group of teenagers and adults who attacked 16-year-old Jason Galleghan at Doonside in Sydney's west on August 4, 2021.
Jason died in hospital two days later.
The teenager sentenced in the NSW Supreme Court on Wednesday pleaded guilty to murder but cannot be named as he was only 14, and several others remain before the courts.
He helped collect Jason from a railway station, striking him 52 times in less than two minutes, kicking him in the head and later stomping on his chest in a spare bedroom of a nearby home.
It was captured in videos later posted online.
The teen had posted on social media hours before the assault that he was "bashing someone today, lmao".
The assault lasted for more than half an hour, however only about seven minutes was recorded and available to the court.
One recording captured the teen saying: "Oi, stop … look at him".
It was submitted he realised the attack had gone too far, which proved controversial.
Acting NSW Supreme Court Justice Robert Hulme watched the footage repeatedly.
"I'm not persuaded it conveys any concern or that he was trying to persuade any of them the assault should cease," he said on Wednesday.
Immediately before he made the comment the teen is heard directing others in the assault, the judge said.
The teen told a psychologist he felt rejected by his father, who left him in the care of an alcoholic mother.
By the time the threat of her children entering state care became very real, her son's behaviour was "increasingly uncontrollable" and he began abusing alcohol and other drugs too.
He was getting into fights and bringing weapons to school before he stopped attending altogether, finding confidence and identity through gang association, and said he felt pressured to contribute to the attack.
The judge said Jason was targeted over "an unsubstantiated and trivial accusation (he) may have taken a pair of earphones" and the teen participated in the assault "as enthusiastically as anyone".
He was satisfied the teen was genuinely remorseful about it, jailing him for at least 10 years on a total sentence of 15 years and six months.
Arrested a day after the attack, the teen will serve his sentence in a juvenile facility until he turns 21 and will be eligible for parole in August 2031, when he will be 24.
Justice Hulme said Jason's mother had described the most terrible experience of losing her child in a victim impact statement, detailing "with considerable courage" the impact on his family and friends.
The judge lamented there's nothing the criminal courts can do to solve that.