Warning: This story contains the name and images of a deceased Indigenous person.

A murdered Indigenous teenager who was chased into bushland and beaten with a metal pole was the victim of a heinous racial attack that has torn at the fabric of society, his mother says.

Mitchell Colin Forth, 27, who was also on trial in the West Australian Supreme Court for Cassius’ murder, was found guilty of manslaughter.

The victim’s mother, Mechelle Turvey, told the trio’s two-day sentencing hearing her son was a gentle giant who was respected by the community and his death had left her and others traumatised.

“The impact of these heinous acts extends far beyond the immediate victims. Families are left devastated, grappling with the unimaginable pain of seeing their loved ones suffer,” she told the court today.

The community wanted a place of safety and trust, but it “now lives under a shadow of fear and uncertainty” after Cassius and the other children were racially vilified, confronted, chased and attacked, Turvey added.

“That’s the truth. If anyone thinks their actions were not racially motivated, many Australians would be left scratching their head,” she said in a victim impact statement.

“The actions of the accused have torn at the very fabric of our society, leaving wounds that will take years, decades, if not lifetimes, to heal and recover.”

Turvey said the convicted men had “glorified” their crimes and no words could fully capture the devastation of losing someone you loved to violence.

“Cassius was not just part of my life,” she said.

“He was my future, my family, my home. The day he was taken from us … my will was shattered.”

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

It was alleged Forth and Palmer aided him in the common purpose, along with Aleesha Louise Gilmore, 23, who was acquitted of a murder charge.

The attack on Cassius in bushland followed a complex series of events that had nothing to do with the victim, the jury heard.

They started four days before the killing when Forth, Brearley, Gilmore and another man who was tried on lesser charges, Ethan Robert MacKenzie, 20, allegedly “snatched two kids off the street” before punching, kicking and stabbing one of them.

Before the attack on Cassius, Brearley and his co-accused allegedly armed themselves with metal poles pulled from shopping trolleys before driving off to search for 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 the field, and Cassius and some other “terrified school kids” fled into nearby bushland.

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

Cassius was struck at least twice, the impact splitting his ear in half and causing bleeding in his brain.

All told, the five defendants variously faced 21 charges over the events of October 9 and 13.

The jury found them guilty of all except Gilmore’s murder charge and a theft charge faced by Brearley.

For 24/7 crisis support run by Aboriginal and Torres Strait Islander people, contact 13YARN (13 92 76).