A Brisbane man believed he was possessed when he allegedly bashed Korean woman Eunji Ban to death.
Alex Reuben McEwan is on trial in the Brisbane Supreme Court for the murder of Ms Ban in the CBD on November 24, 2013.
He has pleaded not guilty to murder, but admitted to her manslaughter, blaming his actions on a "sphere rolling around his head".
His lawyer has argued his schizophrenia made him unable to control his actions and that he had laid bare his mental health issues to his mother, Ruth, three days before Ms Ban's death.
"He said sometimes when he comes home late ... he's just sitting in a park because he feels like he's not normal, not like other people," Ruth McEwan told the court on Tuesday.
"And he's got to make it stop. That's what he said."
McEwan told his mother "it was the sphere" as police arrested him at at his Spring Hill home two days after the alleged murder.
Ms McEwan said her son became withdrawn as a 15-year-old after developing what she suspected was depression.
Through tears she told the court he would yell out "no" and bash his body against the wall of his bedroom during his sleep.
His sister Emma also believed he was possessed at the time of Ms Ban's death, telling the court they had been close up until his mid-teens.
"I spoke to him one last time before he got taken into custody ... he was not sober when it happened and he says he was possessed," she told a friend on Facebook two days after the alleged murder.
"I believe him. He's been showing signs of this ever since he was 16."
Ms Ban was found next to a tree in Wickham Park with head injuries so severe she drowned in her own blood and a paramedic could not immediately determine her gender.
Prosecutors allege she was repeatedly punched by McEwan, then aged 19, while walking to her cleaning job.
Hospitality worker Dean Quinn testified to seeing what appeared to be someone pulling something up stairs at Wickham Park as he walked home from work, and hearing gargling noises as he approached Ms Ban's body.
The trial continues.
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