Juan Miguel Cervantes' pleas of "it's me, it's me Miguel" before his friend killed him with a screwdriver add to a weight of evidence that the attacker was mentally ill, a Sydney judge has found.
Sosiua "Vake" Tonga was on Wednesday found not criminally responsible for the homicide of Mr Cervantes in a shed of Tonga's Eastern Creek property on August 11, 2019.
The NSW Supreme Court was told Tonga's partner Astrid Muller heard yelling from the shed before seeing Mr Cervantes and Tonga emerge, grasping the collar area of each other's shirt.
With a bloodied forehead, the victim called on the partner to "tell Vake it's me, Miguel".
Before ramming his friend back into the shed, Tonga told his partner "he is no good" and asked if she had his back "or do you take his side".
Ms Muller then heard Mr Cervantes say "Vake it's me, it's me Miguel, Vake please, Vake please" before a scream as Tonga plunged the screwdriver into his friend's skull.
Soon after the attack, Tonga told his brother-in-law he was sorry and that he had been trying to get out of the house for a long time due to "demons down the back".
The 36-year-old also asked Ms Muller if she was the devil.
While Tonga was on anti-psychotic medication, he'd appeared to not have taken it and had also used a large amount of methylamphetamine.
That "almost certainly contributed" to his mental state during the attack, Justice Helen Wilson said.
"But that does not diminish the significance of the serious and enduring nature of his underlying schizophrenia, and the profound impact it had on his capacity to accurately perceive events around him and cogently reason about his circumstances," she said.
Tonga's illness often manifested in paranoid and persecutory delusions, including that "bikies" or the mafia were pursuing him and intended his family serious harm.
Justice Wilson gave considerable weight to opinions of two highly regarded forensic psychiatrists, who agreed Tonga did not know that his act was wrong at the time due to his psychosis.
She also found Mr Cervantes' pleas to Ms Muller and Tonga about his identity, was itself strong evidence that Tonga had expressed some delusional belief about who he perceived Mr Cervantes to be.
"It is likely that the accused thought that he was 'a pawn' of bikies sent to kill him, as he said to clinicians and others on receipt into custody," Justice Wilson said.
Both the defence and the Crown had submitted the court should make the mental impairment finding.
Justice Wilson noted Tonga knew the nature and quality of his act as suggested by his immediate call for an ambulance, and his acceptance that he would "go away for a long time".
But she said he did not know that his act was wrong, with his capacity to reason impaired by the psychosis.
As a result of the special verdict to the charge of murder, Tonga will remain in custody and has been referred to the Mental Health Review Tribunal.