SA mental health system failed mother

South Australia's mental health system failed in its duty towards a psychotic woman who suffocated her toddler believing she was expelling an evil spirit, a coroner has found.

State Coroner Mark Johns on Friday handed down his findings at the inquest into the death of two-year-old Duke Zenon Hadley in November 2009 in Adelaide.

His mother, Rachael Hadley, was acutely psychotic when she stood on his mouth and chest to expel an evil spirit.

She was found not guilty of murder but found mentally incompetent.

The coroner found Ms Hadley, then 22, was appropriately discharged from a mental clinic about 11 months before the death.

The Port Adelaide Community Treatment Team then became responsible for her care, but her file was closed in September 2009.

Mr Johns said the cessation of contact should not have happened and had she been afforded proper and appropriate psychiatric care, she might not have relapsed and deteriorated.

"In my opinion it is a result of the unrealistically high workload that the Port Adelaide Community Treatment Team had at that time."

The next opportunity to prevent the boy's death came when Ms Hadley's partner contacted the Mental Health Triage Service for assistance the evening before Duke was killed.

A recording of the phone call sounded as if the person at the other end "was trying to find reasons not to help", he said.

Again, the coroner said, it seemed the listener "was working in an environment in which he felt more obliged to ration a precious resource" than to be encouraging of the partner's efforts to get help.

His recommendations included regular audits of community mental health teams to ensure they are adequately and appropriately staffed and have systems to track patients and appointments.

The fact the mental health system did not ensure continuity of care should be addressed as a matter of priority, he added.