"The medical records documented that he suffered a seizure at the accident, loss consciousness and was subsequently transported to Starship by ambulance."
Dr McGinn said the accident resulted in him suffering from post-traumatic amnesia, meaning he was unable to retain information for some time after the accident.
He then began to demonstrate behaviours at his school that caused management some concern. The school sent a letter to the Kauri Centre - a child and adolescent mental health service.
Dr McGinn said the letter described the boy locking himself in the bathroom and hurting himself, and a time he did the same in the classroom.
"Once [the accused] was banging his head on the classroom wall and when his teacher asked why he was doing this, he said because he 'didn't want to feel anymore,"' said Dr McGinn.
The letter also talked about how he socialised with other children. Dr McGinn said he'd be verbally and physically intimidating.
"If he felt he was being slighted in any way he will act without remorse," she said, reading from the school's letter to the Kauri Centre.
Dr McGinn says a lot of this was due to his brain injury. She said he didn't demonstrate any of these behaviours prior to the accident.
An earlier testimony by the boy's older brother, who also has name suppression, showed the accused also started taking synthetic drugs.
He said their mother bought and sold drugs out of the home the accused lived in.
"My mum helped him," he said. "She was giving him marijuana? to stop him from wanting synthetics."
The 16-year-old witness said he didn't live in the same house as the accused, because he'd "got out" three years earlier.
The boy's co-accused is 13-years-old and is charged with manslaughter. Both are accused of assault with intent to rob and both boys have name suppression
Earlier, the older brother of the 14-year-old boy accused of murders told the court how his little brother took synthetic drugs and lived in a drug house.
The 16-year-old witness said he did not live in the same house as the accused, because he'd "got out" three years earlier.
But he'd go around there often, he said, and the accused would look like a zombie.
"Whenever I went there he would pretend he wasn't using [synthetic drugs]," he said. "But I knew he was using synthetics. He would go to like a zombie."
The boy told the court that there would often be people around that he didn't know very well and couldn't recall their names.
The house was a place people went to get drugs, he said.
"They were mostly buying synthetics. Everyone was smoking drugs in the house? it was a drug house. You came there and smoked drugs there," he said.
The boy said when the accused smoked synthetic drugs, he and their mother would tell him not too.
"My mum helped him," he said. "She was giving him marijuana? to stop him from wanting synthetics."
The witness said he'd lived in at least 10 different houses and from what he could remember, had been to at least eight schools.
He said he'd spent half his life in homes he was placed in by Child Youth and Family and believed his little brother would have been through a similar sort of thing.