A Sydney man who killed his whole family and their pet chihuahuas has been found not guilty of murder by reason of mental illness.
Carlos Lopez, 44, has also been declared not guilty of animal cruelty because a NSW Supreme Court judge has found he never intended to inflict severe pain on the two dogs.
In a judge-alone trial, Justice Peter Garling found Lopez had fatally stabbed his mother Olga Novosadek, his stepfather Pablo Novosadek and his stepbrother Raul Novosadek at their western Sydney home in the early hours of July 29, 2012.
"I am also satisfied beyond reasonable doubt that he did so intending to kill each of them," Justice Garling said on Friday.
But he found Lopez suffered from schizophrenia at the time of the killings and was therefore not guilty.
"I am persuaded that by reason of his mental illness, Lopez was suffering from a defect of reason such that he did not know what he was doing was wrong," Justice Garling said.
Crown expert and forensic psychiatrist David Greenberg last week told the court that at the time of the stabbings, Lopez believed extra-terrestrial demons were using his family members as hosts.
"He felt he was morally justified in acting that way because the demons were descending ... and in order to protect them and save them he had to kill them," Professor Greenberg said.
Lopez has been ordered into custody at the Long Bay Prison Hospital psychiatric ward or in any place determined by the Mental Health Review Tribunal until released "by due process of law".