Trevor Noone has been sentenced to 13 years in prison for his part in the murder of teenager Daniel McAnaspie.
The 29-year-old, with an address in Blanchardstown in Dublin, pleaded guilty in February to Daniel's manslaughter.
The 17-year-old's decomposed body was found in a drainage ditch in Co Meath, almost three months after he was stabbed to death on 26 February 2010 at Tolka Valley Park.
Passing sentence Justice Patrick McCarthy said the circumstances of Daniel's death put Noone's actions in the most serious category of assault to manslaughter cases.
He said the events were of "quite a horrific nature" and Daniel did "nothing whatsoever" to deserve what happened to him.
Justice McCarthy said Daniel did not have an easy life - he was an orphan at the time of his death and was in the care of the Health Service Executive.
On the night he died his carers dropped him off in Finglas where he met some friends and then travelled to Blanchardstown where he met Trevor Noone and Richard Dekker.
Dekker was convicted of Daniel's murder in a trial that ended in March.
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
The evidence in the trial showed that in the early hours Noone and Dekker lured Daniel to a secluded area in Tolka Valley Park on the pretence that they were going to fight some "lads from Corduff".
Instead, Daniel was stabbed multiple times with a garden shears.
Justice McCarthy said simply mentioning the weapon shows how grave the offence was.
He also noted that Noone told gardaí that he knew Dekker was carrying a garden shears and that he intended to give Daniel "a few digs".
"That is why this must be at the top end of the range for offences of this nature," he said.
Outlining Noone's circumstances, he said he had been unemployed all his life and has a modest sense of a moral compass.
Reading from a psychological report he noted that Noone has a schizoid personality, cognitive difficulties and an emotional disconnection from the social world around him.
Noting his history of offending, including firearms and drugs offences, he said Noone shows "scant respect for others in society".
Given all of that, he said the appropriate sentence would be 18 to 20 years, but taking into account his guilty plea and signs of remorse, he reduced it to 13 years.
His sentence will be backdated for time already served.
Noone was led away to the sound of Daniel's family applauding.
As they emerged onto Parkgate Street Daniel's sisters held a large poster in remembrance of their brother.
Detective Superintendent Colm Fox, who led the investigation, said: "While today's events will not bring Daniel back, it brings some closure to the family knowing the perpetrators of this shocking act of violence have been dealt with by the courts."
