Three young misguided vigilantes who brutally assaulted a Canberra man, bound him and left him for dead will be released from juvenile prison before their 22nd birthdays.
Peter Keeley died after being lured to a secluded area in Broulee on the NSW south coast with the expectation he would meet an 18-year-old man for sex.
Instead, a 17-year-old who had posed as the young adult on hook-up app Grindr began belting him before his two mates emerged from bushland to join in the ambush.
"These were three youths who were friends and apart from some illicit drug use, were law-abiding and of good character," NSW Supreme Court Justice Michael Walton said on Tuesday.
"The offending was guided by a dangerous and misguided idea which according to (one boy) 'all went terribly wrong'."
During the attack on February 2, 2020, Mr Keeley was hit in the face repeatedly.
He fought back, suffering a defensive wound to his arm, before falling to the ground and having his ankles and wrists bound.
One teenager then gagged him with packing tape before the trio dragged him to a power pole, sat him upright and left.
"It was undoubtedly a frightening experience for the deceased," the judge said.
"When left, he was in a very vulnerable position - left unable to move or call for assistance. He was left alone in a remote area."
His body was found later that day.
Dirt was found on his battered face, while the teenagers' DNA matched that found on the tape around Mr Keeley's limbs.
The boys were arrested 11 days after the fatal assault.
"I didn't do it on purpose, it was an accident, I didn't want it to happen," the organiser of the ambush told his father when police arrived.
That boy, a Year 12 student, had started messaging Mr Keeley on February 1 on Grindr and learned of the man's apparent keen interest in young guys and girls, including those under the age of 18.
After organising to meet the Canberra man in Broulee, he looped in his two friends about a plan to ambush Mr Keeley and deal out vigilante justice.
The teenagers, all then aged 17, were each charged with murder but two were acquitted at trial this year, prompting prosecutors to withdraw the murder charge against the third teenager.
Instead, each accused pleaded guilty to detaining a person with special aggravation.
Justice Walton said the now-adults had prospered in juvenile detention, had good prospects of rehabilitation and were unlikely to reoffend.
All had shown real remorse and insight into their offending, he said.
He ordered the organiser, now aged 20, to serve a minimum of three years and 10 months in prison. A co-offender, now 19, was jailed until January 2023 while the third offender, who has extensive mental health issues, is eligible for parole from Tuesday.
Having heard medical experts' concerns that the young men would "fall through the cracks" if moved to an adult prison, Justice Walton ordered prison authorities allow the men to serve their sentences in juvenile detention.
