WARNING: Aboriginal and Torres Strait Islander readers are advised this story contains images of people who have died

Three “monsters” convicted over the death of Indigenous teenager Cassius Turvey have learnt their fate in court.

Cassius, 15, died in hospital 10 days after he was chased into bushland and beaten with a metal pole in Perth’s eastern suburbs on October 13, 2022.

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WATCH THE VIDEO ABOVE: Three people convicted over Cassius Turvey’s death sentenced in Perth.

Jack Steven James Brearley, 24, and Brodie Lee Palmer, 30, have been sentenced to life behind bars after they were convicted of murder in May.

Brearley will be eligible for parole after 22 years and Palmer 18.

Mitchell Colin Forth, 27, was convicted of manslaughter and sentenced to 12 years, eligible for parole in 10.

In his sentencing remarks, Chief Justice Peter Quinlan said the teenage victim “was robbed of his life and of his promise ... all because you killed him, Mr Brearley”.

“You cut short Cassius Turvey’s life in an act of aggression, violence and brutality, which, regardless of the sentences I impose today, can never be made right,” he said.

“You too are responsible for his death, Mr Palmer and Mr Forth, in different ways.”

Quinlan said Palmer had failed to accept responsibility for his crimes and there were few mitigating factors to reduce his sentence.

“You do not have the benefit of a plea of guilty ... and you do not have the benefit of good character,” he said.

Justice Quinlan said Forth was never the main offender in the shameful course of events but always there in the background.

The sentences were met with applause from dozens of supporters inside the court.

The trial heard Brearley delivered the fatal blows while “hunting for kids” because somebody had smashed his car windows.

Forth and Palmer were accused of aiding him in the common purpose, along with Aleesha Louise Gilmore, 23, who was acquitted of a murder charge.

The victim’s mother, Mechelle Turvey, said it was hard to say if justice had been served.

“Yes I’m happy with the verdicts, I’m happy with the sentencing, apart from Aleesha Gilmore, but Cassius isn’t here with us,” she said outside court.

“No mother should have to visit the grave of a 15-year-old innocent child who (did) absolutely nothing.”

She described her boy’s attackers as “monsters”.

“I don’t really care what they’re thinking about. They weren’t thinking on the 13th of October. Now they want to back-pedal and they’re sorry. They’re all monsters,” she said.

‘Doesn’t undo what’s done’

Detective Senior Sergeant Stephen Cleal said he was proud of the Turvey family.

“Whatever sentencing happened it doesn’t undo what’s done,” he said.

“I’m very proud of the family. I’m proud of Mechelle and I’m happy that the next phase of their healing can start.

“For me today when you (Mechelle) read out the victim impact statement, that was a powerful moment, really powerful moment.

“So I’m just very proud of how the family went and I’m very happy that the judge, his honour, acknowledged the children (witnesses) because that would have been very hard for the kids and I have a real heart for that and they’re victims of this as well.”

‘Your attack was persistent and sustained’

Brearley and his co-accused allegedly armed themselves with metal poles pulled from shopping trolleys before climbing into Palmer’s ute and driving off to search for some youths.

About the same time, Cassius and a group of about 20 fellow students caught a bus to the same area to watch a fight being talked about on social media.

Brearley, Forth and Palmer intercepted them near a field, and Cassius and some other “terrified school kids” fled into bushland.

It was there that Brearley caught up with him before the teen was knocked to the ground and hit in the head with a metal pole, causing bleeding in his brain.

“Mr Brearley, you were the person who killed Cassius Turvey in that fit of rage and brutality,” Quinlan said.

“You went onto that field looking for someone, anyone to inflict serious injury on, and you carried out that intention with unflinching violence.

“While you did not intend to kill Cassius Turvey, your attack was persistent and sustained and only stopped by the arrival of Mr Palmer.”

Gilmore and another man, Ethan Robert MacKenzie, 21, were convicted over other crimes - the abduction and assault of two teens four days before Cassius was attacked - also involving Forth and Brearley.

Gilmore was sentenced to one year and three months, conditionally suspended for 24 months.

MacKenzie, who was not charged with the murder of Cassius, received two years and six months and will be eligible for parole in November.

First Nations people seeking mental health support should contact Aboriginal & Torres Strait Islander crisis support line 13YARN on 13 92 76 or 13yarn.org.au.

If you need help in a crisis, call Lifeline on 13 11 14. For further information about depression contact beyondblue on 1300 224 636 or talk to your GP, local health professional or someone you trust.