A teenage girlfriend allegedly at the centre of a love triangle that triggered a series of violent events before an Indigenous teenager died is expected to front a murder trial.

WARNING: Aboriginal and Torres Strait Islander readers are warned the following article contains names and images of a deceased person.

Cassius Turvey, a 15-year-old Noongar Yamatji boy, died in hospital 10 days after he was “caught, knocked to the ground and deliberately struck to the head with a metal pole” in Perth’s eastern suburbs on October 13, 2022.

Jack Steven James Brearley, 23, Brodie Lee Palmer, 29, Mitchell Colin Forth, 26, and Aleesha Louise Gilmore, 23, are on trial in the Western Australian Supreme Court for his murder, which they deny.

Prosecutors say Cassius’ death was “the end point of a complex series of events that had absolutely nothing to do with him”.

They started on October 9 when Forth, Brearley, Gilmore and another man allegedly “snatched two kids off the street” and punched, kicked and stabbed one of them.

The incident was allegedly sparked by a “love triangle” involving Gilmore’s 14-year-old brother, his girlfriend, who cannot be named for legal reasons, and another teen of similar age and social media exchanges about the boys fighting.

The next event allegedly happened three days later on October 12 when a group of school-aged kids went to Gilmore’s home and “almost certainly in retribution” smashed the windows of Brearley’s car, the jury was told on the first day of the trial.

The following day, Gilmore’s brothers warned her that a group of teens could be coming to their family home, where Brearley also lived, looking for a fight.

Brearley, Forth and Palmer allegedly armed themselves with metal poles pulled from shopping trolleys and knuckle dusters and drove off to search for youths with Gilmore.

“Somebody smashed my car and they’re about to die,” a prosecutor told the jury Brearley allegedly said.

They allegedly found a group of about 20 school-aged teens, including Cassius.

Brearley was “hunting for kids with a metal pole” and Cassius and some of the other “terrified school kids” fled into nearby bushland, the court was told.

“Cassius didn’t make it as far as the fence when the accused Brearley caught up with him,” the prosecutor said.

“He was struck to the head at least twice.”

The trial continues today when Gilmore’s younger brother’s girlfriend is expected to be called as a witness to give evidence.

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