Warning: This article contains the name and images of an Indigenous person who has died. His family has given permission to use his name and image.

Two men have been sentenced to life imprisonment for murdering an Aboriginal schoolboy, in a case that shocked Australia.

Cassius Turvey died of head injuries after a brutal assault on the outskirts of Perth in October 2022. The 15-year-old’s killing prompted nationwide protests and vigils, also sparking debate on pervasive racism in the country.

The killers, Jack Brearley and Brodie Palmer, were “callous and lacking in empathy” as they chased Turvey down and savagely beat the Noongar Yamatji boy with a metal pole, Justice Peter Quinlan told a packed courtroom on Friday.

Mitchell Forth, who was convicted of manslaughter, was sentenced to 12 years in jail.

The gallery cheered as Justice Quinlan handed down the sentences, while Cassius’ mother Mechelle Turvey burst into tears, local media reported.

Prosecutors had told the trial the attack on Cassius was the culmination of a complex series of tit-for-tat events that had nothing to do with him.

The vigilante gang responsible for his death had been “hunting for kids” because somebody had damaged Brearley’s car windows.

Brearley, 24, and Palmer, 30, had each blamed the other for Cassius’ death, with Brearley also alleging that he acted in self-defence as Cassius was armed with a knife.

Justice Quinlan rejected that as a “complete fabrication”, and found that it was Brearley who had delivered the fatal blows.

“Cassius Turvey was completely and utterly innocent of any wrongdoing whatsoever. The only reason that he was the person killed… was that he was the person you happened to catch,” Justice Quinlan said.

Brearley had shown “no remorse whatsoever”, the judge added.

“You cannot make amends when you don’t acknowledge the pain that you have caused.

“You cannot be remorseful when in an effort to avoid responsibility… You seek to frame an innocent man and when that does not work you give false evidence that your co-accused was in fact the killer,” the chief justice said in a scathing rebuke reported by ABC News.

Palmer did not physically strike Cassius, but Justice Quinlan ruled that he was “equally responsible but not equally culpable”.

The group had also assaulted other Aboriginal teenagers in what the judge described as “so-called vigilante justice [that] was completely misdirected”.

A fourth offender, Ethan MacKenzie, was handed a two-and-a-half years jail term for his part in some of the other assaults.

In one case, a 13-year-old boy’s own crutches were used to beat him, causing bruising to his face.

Justice Quinlan condemned Brearley, Palmer and Forth for their “celebration” after the assaults, calling it a “grotesque display of your complete disregard of the lives of the children you had attacked”.

In her victim impact statement on Thursday, Cassius’ mother Mechelle Turvey said the actions of the three men were racially motivated.

“Cassius was not just part of my life, he was my future,” Ms Turvey said. “There are no words that can fully capture the devastation of losing someone you love to violence.”

While Justice Quinlan did not find the attack to be motivated by race, he said the attackers’ use of racial slurs “rippled” through the Aboriginal community and created “justifiable fear”.

“The fear is real and legitimate. You are responsible for that fear,” he said.

Palmer is eligible for parole in January 2041, while Brearly will be eligible from October 2044, the Australian Associated Press reported.