Some aspects of what happened are suppressed, but it can be reported that at 6.30pm on September 11, McGowan was at home when he became anxious and agitated.
He picked up a large knife from the kitchen and walked to the lounge, where his parents were.
McGowan approached his father from behind and stabbed the side of his head and abdomen. McGowan's father suffered a wound to the ear, a deep wound to his body and a punctured liver.
McGowan's mother screamed and tried to intervene, but he stabbed her, cutting her face and inflicting a fatal wound to the abdomen.
McGowan's father saw his wife on the coach and disarmed his son, who then ran downstairs, picked up his backpack and left the house.
Emergency services were called and found McGowan's parents in a critical condition. Mrs McGowan deteriorated rapidly at the house, where she died, and Mr McGowan was taken to hospital by ambulance.
Police found Max McGowan a short distance away, after he washed blood of himself at a stream.
"When spoken to he admitted stabbing his parents ... He told the police he couldn't believe that had happened,'' Crown prosecutor Warren Cathcart said.
Max McGowan was to have gone to work that day, but turned back on his trip there, because he didn't feel well.
The court heard from the expert witnesses that McGowan had a history of mental illness and depression. He suffers from paranoid schizophrenia and sometimes heard voices in his head, but was now on medication.
"He still feels depressed, aggravated by guilt over what he's done,'' Prof Mellsop said.
Max McGowan was a loner who had trouble holding down a job, but had completed a bachelors degree, Prof Mellsop said. He was interested in art and computer games.
Prof Mellsop said "on the balance of probabilities'' McGowan didn't know that what he was doing was morally wrong.
The court was told McGowan now has some contact with his brother, but none with his father.
"I still love my parents. This has been the worst experience of my life,'' McGowan told Dr Chaplow during an interview.
