Court hears chilling Triple '0' call

"He's killed my wife, he's killed her ... Ah, Christ. I told you we had to put him away."

These were the words screamed by John Stables after discovering his wife had been stabbed to death by their son.

Enriquita Stables, 50, died after being pierced numerous times in the stomach with a sword wielded by her son Luke at their Dean Park home in Sydney's northwest on September 6, 2012.

Luke Stables, 29, has pleaded not guilty on the grounds of mental illness to his mother's murder and the wounding of his brother Mark.

At the opening day of his judge-alone trial on Thursday, the Supreme Court heard the frantic Triple 0 call made by John Stables after discovering his wife's body.

Screaming "Ah" repeatedly, Mr Stables yells: "He's killed my wife."

"You've done it now, you've done it now ... he's killed her, he's stabbed her."

Later, Mr Stables told police "my wife was trying to control him, but she couldn't... He went crazy and used to go crazy quite often".

In a report tendered on behalf of the crown, forensic psychiatrist Bruce Westmore said Stables suffered from a complex form of epilepsy which often resulted in seizures.

Stables, Dr Westmore said, suffered from a range of mental health issues, including mild retardation and temporal lobe epilepsy.

At the family's home that night, police recorded a brief interview with Luke Stables in the back of a police van.

When they asked why he stabbed his mother, the 29-year-old said: "I don't know ... I went crazy."

There is no dispute between the crown and the defence that Stables should be found not guilty of murder by reason of mental illness.

The court will still hear evidence from Dr Westmore on Thursday.

The trial before Justice Peter Hidden continues.