A mentally ill woman killed her sleeping mother while believing the older woman was the devil, screamed "for God to come down" and later expressed disappointment she wasn't on the news, a Sydney court has been told.
Siham Khatib, 35, was on Wednesday found not guilty on mental illness grounds of murdering her mother Noura Khatib, 63, in their South Granville home in January 2018.
About 6.15am on January 25, the youngest of six daughters walked downstairs, grabbed a 30cm knife from the kitchen and stabbed her mother.
The older woman had been dozing on the couch but began screaming as the knife went into her on the first of five occasions.
Pulled away by her older sister, Khatib dropped the knife and ran into the street, stopping cars and screaming for "God to come down", NSW Supreme Court Justice Michael Walton said.
Finding her not guilty, he said Khatib had been labouring under a "defect of reason".
"As a result the accused did not know ... the act was wrong," Justice Walton said.
Forensic psychiatrists earlier told the court the woman had bipolar one disorder, also known as manic-depressive disorder, and was affected by the condition at the time of her mother's death.
Dr David Greenberg said Khatib was "acutely psychotic" during the police interview conducted after her mother's death.
She claimed she was the queen and expressed sadness she wasn't on the news, but was happy her home was now famous on TV as "a devil's house".
"She began to sing in the interview ... and spoke about wanting to celebrate," Dr Greenberg told the court.
"In keeping with her manic phase, she was totally euphoric."
Dr Greenberg said Khatib's condition took about six weeks to stabilise.
Dr Richard Furst said Khatib had a history of non-compliance with medications and had been a patient at the Cumberland public psychiatric hospital five times between 2011 and 2017.
He said her reasoning was defective at the time of the stabbing.
"(She had) prominent delusional thinking and the belief that her mother was the devil and the residence was the devil's home," Dr Furst said.
He added there were no logical reasons for the stabbing, which "came out of the blue" without argument or provocation.
Khatib, who remained expressionless when the verdict was handed down, will remain in custody before a Mental Health Review Tribunal hearing.