Jordan Brodie Miller who killed his girlfriend Emerald Wardle believing she was a 'demon' after taking LSD has 20-year-jail sentence quashed

A man has overturned a 20-year jail sentence for murder after a court found delusions his girlfriend was a demon as he strangled her were the first onset of schizophrenia.

Jordan Brodie Miller took LSD 11 days before violently attacking and killing his partner Emerald Wardle at a home at Metford, in the NSW Hunter region, in June 2020.

He later told a triple-zero operator and police that he believed Ms Wardle was a demon at the time of the attack.

Miller was convicted of murder by a NSW Supreme Court jury in June 2022 and sentenced to a maximum of 20 years in prison, with a non-parole period of 13 years.

A key issue at the trial was whether he killed his girlfriend while experiencing symptoms of undiagnosed schizophrenia or drug-induced psychosis.

He appealed both the conviction and sentence, telling the NSW Court of Criminal Appeal that since the trial he had been diagnosed with schizophrenia and his symptoms were ongoing.

On Friday, the court unanimously upheld the appeal saying the evidence was all 'one way' that he had symptoms of schizophrenia when he killed Ms Wardle.

'The court is satisfied on the balance of probabilities that the applicant had a 'mental health impairment', as defined, namely schizophrenia, at the time he carried out the act of killing Ms Wardle,' the three-judge panel wrote.

'Although he knew the nature and quality of his acts in causing the death of Ms Wardle, he did not know the act was wrong because of his psychotic delusion at the time.'

Miller was found not criminally responsible for the killing.

His case will be sent to the Mental Health Review Tribunal, which will determine how and where he will be treated.

In overturning the conviction and lengthy jail sentence, the appeals court expressed sympathy towards Ms Wardle's family.

'The court acknowledges that the loss of Emerald Wardle has caused enormous pain to her family from which they will never recover,' the judges wrote.

Lifeline 13 11 14

beyondblue 1300 22 4636