A MAN who strangled a 16-year-old boy to death at a unit in Charlestown last year was suffering from a temporary, substance-induced psychosis directly related to his use of methamphetamine, a jury has been told.
Chadley Sheridan, 25, would not have suffered an episode of psychosis around the time he killed the teenager on March 15 had he not been intoxicated by drugs, consultant forensic psychiatrist Dr Kerri Eagle gave evidence on Friday.
Both medical experts, Dr Eagle and forensic psychiatrist Dr Olav Nielssen, agree that at the time he strangled the teenager while he was asleep in his bedroom, Mr Sheridan was psychotic, experiencing auditory hallucinations and bizarre delusions and was not able to reason the wrongfulness of his actions.
But what caused the psychosis - whether it was substance-induced or the result of an underlying and likely chronic psychotic illness - and whether Mr Sheridan has available to him the defence of mental health impairment has been the focus of the week-long trial in Newcastle Supreme Court.
Dr Eagle, the final prosecution witness, said at the time of the killing, Mr Sheridan was "experiencing a substance-induced psychosis, directly related to his intoxication with substances, most particularly methamphetamine."
She said the psychotic symptoms reduced as the drugs were excreted from his body and there was no evidence he had suffered another episode of psychosis or been treated with antipsychotic medication since his arrest.
Forensic psychiatrist Dr Olav Nielssen gave evidence that Mr Sheridan's impairment on the night was not caused solely by using drugs but they may have exacerbated his underlying mental illness.
Mr Sheridan had been drinking alcohol and using drugs on the evening of March 15, 2021, when the teenager's father and his father's friend left the unit about 10pm, leaving Mr Sheridan in the loungeroom playing video games and the teenager asleep in his bed.
When the teenager's father returned about an hour later, Mr Sheridan was crying and upset and then later was "unable to settle down", the jury has heard.
It was not until after midnight, when the teenager's father checked on him in his bedroom and found his body on the floor, that the alarm was raised and paramedics were called.
Mr Sheridan fled the unit a few minutes later and was arrested at a service station at Thornton about 1.50am.
The trial continues.
