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

An Indigenous teenager was spotted holding his bloody head after being chased into bushland by two men with metal poles, a murder trial has been told.

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

Aleesha Louise Gilmore, 23, her boyfriend Jack Steven James Brearley, 23, and his mates Brodie Lee Palmer, 29 and Mitchell Colin Forth, 26, are on trial in the West Australian Supreme Court charged with murdering Cassius.

A young woman, who cannot be named for legal reasons, told the jury on Monday she caught a bus with Cassius and a group of other teens to a grassy open space near a TAFE college following talk about a fight.

After they arrived a black ute drove past with a woman and three men.

The witness said someone in the group yelled: “You smashed our windows, you black c—-“.

The now-19-year-old said the ute returned sometime later and “the three men jumped out”.

She said the trio continued yelling about the smashed windows and the teens denied having a hand in the incident.

“I remember seeing all of them walk back towards the car to grab weapons,” she said.

“Really skinny kind of long poles.”

The witness described one of the men as muscular and said the other two were skinny.

“The boys started running and the men were chasing after them,” she said.

She also said Cassius was among the teens fleeing from the men and that they fled into bushland near the TAFE.

The witness said the muscular man and one of the skinny men ran into the bush after the boys with metal poles.

She said Cassius later emerged from the bush and he was “holding his head and it was bleeding down like his head and his ear, and he was crying”.

Prosecutor Ben Stanwix has previously said Gilmore got out of the ute before it returned to the teens and that Brearley, armed with a metal pole, attacked two teens in the group before climbing back into the ute with Palmer and Forth and driving after some of the other teens in the group who had run across the grassy open space.

Cassius was among them and Brearley “hunting for kids” struck him on the head at least twice. One blow split his left ear in half and another lacerated his forehead.

Stanwix said Brearley “was filled with fury about his broken car windows”, which happened a day earlier, and about threats communicated via social media that a group of “kids” could damage the home he shared with Gilmore.

Brearley allegedly later bragged about his “vigilante violence”, saying: “He was just lying in the field and I was striking him with the trolley pole so hard so he learned his lesson”.

Prosecutors say Forth, Palmer and Gilmore helped Brearley and knew his intent.

The smashed car windows were part of a series of escalating tit-for-tat incidents that started on October 9 when some of the accused allegedly “snatched two kids off the street” and unlawfully detained them, punching, kicking and stabbing one of them.

The incident was triggered by a “love triangle” involving Gilmore’s 14-year-old brother and another teen of similar age, and social media exchanges about the boys fighting.