NSW prison officer performing duty when he shot inmate dead, trial told

WARNING: Aboriginal and Torres Strait Islander readers are advised this story contains images of a person who is deceased.

A custody officer on trial for murder was performing his duty as trained when he repeatedly warned an escaping prisoner before shooting him dead, his lawyer says.

Dwayne Johnstone, 43, was shot once in the back about 11 seconds after he started running from NSW corrections officers outside Lismore Base Hospital in March 2019.

Prosecutors allege the man who fired the fatal shot intended to cause really serious injury or knew death was a probable consequence and had no lawful excuse to shoot the restrained prisoner.

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But the officer was fulfilling a duty to prevent an escape, believing he and his colleague wouldn't be able to chase down the running Johnstone, a jury was told on Thursday.

"He did not do so out of malice, out of revenge, out of anger," defence barrister Phillip Strickland SC said in his opening address to the NSW Supreme Court.

"He did so to prevent Mr Johnstone from escaping and that is what his duty as a corrections officer required him to do."

Officer A, as he is known for legal reasons, yelled "stop or I'll shoot" twice and fired two warning shots, as per training for dealing with an escape, Strickland said.

"You must give a warning to the person escaping to give them a chance to stop. Not once but several times," he said.

The Crown said Johnstone was posing "no risk to any person" when shot on the ramp of a closed doctors' surgery.

But the defence said Johnstone was heading towards a car park beside the surgery, giving Officer A "very little time indeed to make the decision in terms of discharging his duties".

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The jury has seen grainy CCTV footage of the March 15 incident, capturing Johnstone running, the officer giving chase, Officer A firing his gun the first two times, and the escapee later falling to the ground.

"The Crown will no doubt play again and again this footage, but the issue for you to consider ... is to look at the matter from the perspective of (Officer A)," Strickland said, saying the CCTV distorted the actual distances between the men.

Johnstone had been arrested the day before for allegedly assaulting a person and possessing a Taser.

After being refused bail by Lismore Local Court about 2.30pm on March 15, he began weeping and told the magistrate: "I'm going to have a fit - I don't have my medication."

Johnstone appeared to then have a fit in the courthouse cells, leading to a medical assessment and transfer to the local hospital, the jury has been told.

He was discharged about 7.30pm.

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While being escorted by Officer A and his colleague towards a Corrective Services van parked at the hospital, Johnstone bumped the other officer and ran across the road.

At the time, his wrists and ankles were restrained.

The trial continues.