A 26-year-old South Australian man has pleaded not guilty to the fatal shooting of a police officer who was responding to an emergency call at a rural property.

Jadyn Stimson is accused of murdering Brevet Sergeant Jason Doig, 53, at a property in Senior, about 15km north of Bordertown in November.

He’s also denied the attempted murder of Sergeant Michael Hutchinson during the same incident.

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Police were responding to reports an animal had been shot when Stimson allegedly opened fire.

Doig, 53, of Lucindale Police Station, died of gunshot wounds at the scene.

Hutchinson, was also shot and taken to hospital for treatment of non-life threatening injuries.

Police then fired on Stimson, who suffered life-threatening injuries and was flown to the Royal Adelaide Hospital for treatment.

His lawyers argued the 26-year-old had an undiagnosed mental health condition at the time of the incident.

Outside court, lawyer Andrew Graham said the investigation into Stimson’s mental health was ongoing.

“That investigation needs to happen in the Supreme Court so he’s pleaded not guilty,” Graham said.

He said Stimson has been diagnosed with a psychotic illness.

The 26-year-old will stand trial in the Supreme Court in September.

He remains in custody at mental health facility James Nash House.