The man charged over the fatal shooting of police officer Jason Doig in South Australia’s south-east has pleaded not guilty to murder and attempted murder.

Jaydn Harley Stimson, 26, appeared in the Adelaide Magistrates Court via video link from mental health facility James Nash House.

He is accused of killing Brevet Sergeant Doig, 55, at a rural property at Senior, north of Bordertown, in November.

He is also charged with the attempted murder of Sergeant Michael Hutchinson, who suffered non-life threatening injuries when responding to the incident alongside a third officer, Constable Rebekah Cass.

Mr Stimson is currently remanded at James Nash House under the state’s Criminal Law Consolidation Act, which provides guidelines for an accused who may have a mental impairment defence.

Brevet Sergeant Jason Doig was the officer-in-charge of Lucindale Police Station.(Supplied)

In April, Mr Stimson’s lawyer Andrew Graham asked the court to formally remand his client in the mental health facility.

He told the court Mr Stimson had been housed at the Oakden facility since January without a court order and it was “now appropriate that order be made”.

“There has been a diagnosis of a psychotic mental illness. In my submission it’s appropriate that it be noted,” he told the court in April.

“The objective elements of the offence will be admitted.”

Speaking outside court today, Mr Graham said an investigation into his client’s mental competence was continuing.

He said it was likely that the defence would argue Mr Stimson was suffering from a psychotic illness at the time of the alleged murder. 

“We are still waiting on a final report from a psychiatrist,” he said.

Mr Stimson will remain in custody at James Nash House and will face the Supreme Court for arraignment in September.