Ten days later, the 15-year-old Noongar Yamatji boy died in hospital, with prosecutors alleging 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 Tuesday that two men confronted two students she was with.
The court was previously told Cassius and a group of other students had gone to a grassy open space after school to watch a fight and then fled into a bush area after three men pulled up in a ute.
"The skinny fella and the tall dude, the bigger guy ... they ran into the bush," the witness told prosecutor Ben Stanwix.
She said the lean man was carrying a pole.
The witness, who was 16 at the time of the alleged incident and is now 18, said she saw Cassius emerge from the bush.
"I seen Cassius crying, he was on his own, he was walking towards everyone ... they said he was bleeding but he kept saying he was fine," she said.
"His ear was like in half."
A young man, who also cannot be named, told the court he was assaulted by one of three "white skin" men who arrived in the "black off-road car".
He said one of the men was skinny, another wore a "tradie" shirt and had blonde hair and the third was "kind of chubby" and short.
"Everyone started running except the two girls," he said, adding he also stayed put because he was using crutches to get around.
"The skinny one and the one in the tradie shirt both had poles.
"The skinny one hit me on the nose and started acting aggressively."
He said one of the men took his crutches and a hat he had been wearing and put them in the ute.
"My nose like hurt for a week," he said.
The boy, who was 13 at the time, said he walked to a TAFE college near the bush to find his friends who had fled and spotted Cassius on the ground.
"He was bleeding from his ear and from the top of his head," he said.
Mr Stanwix has previously said Gilmore had left Brearley, Forth and Palmer before they confronted a large group of teen students, who had gathered at a green open space after school.
He alleged Brearley chased Cassius down and struck him on the head at least twice. One blow split his left ear in half and another lacerated his forehead.
Mr 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 incidents were 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.
The trial continues.
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