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       Constable Nathan Parker, right, is charged with assaulting a peace officer, assaulting with intent to resist arrest, and assault with a weapon. The 55-year-old was shot multiple times by a sergeant when an altercation broke out during an investigation in 2018.

       Molly Hayes/The Globe and Mail

       “Can you confirm it’s blue-on-blue shots fired?” the Niagara Regional Police dispatcher asked, after Detective Sergeant Shane Donovan radioed in an ambulance request for a downed officer.

       “Confirmed,” Det. Sgt. Donovan recalls replying, as Constable Nathan Parker lay on the ground, cursing up at him as blood spilled from his neck. “He did pull a gun on me, but I shot him.”

       Snippets of radio calls from the frantic moments following a rare officer-on-officer shooting were played in a Hamilton courtroom Wednesday, on the second day of trial for Constable Parker.

       The 55-year-old is charged with assaulting a peace officer, assaulting with intent to resist arrest, and assault with a weapon against his colleague on a rural Pelham, Ont., road in November, 2018.

       Ontario police officer says he shot colleague during confrontation out of fear for his own life

       Det. Sgt. Donovan – who was also originally charged in the case, but had his charges dropped in 2019, after the Crown cited no reasonable prospect of conviction – testified that he was attacked by Constable Parker, and drew his gun only after the junior officer shoved and punched him, and then came at him with a baton. He only fired, he said, after the constable drew his own service pistol.

       It was a dispute over a bathroom break, court heard, that sparked the confrontation that afternoon. Constable Parker, a uniform officer, had been assigned that morning to help Det. Sgt. Donovan block a roadway so that officers from the collision reconstruction unit could collect evidence they needed for a crash investigation.

       At some point, court heard, Constable Parker left his post unmanned, allowing traffic to flow through. When he returned, Det. Sgt. Donovan told him to let him know of his absence next time.

       The constable snapped back at him for not having his radio, and Det. Sgt. Donovan reminded him of his rank.

       From there, he testified, the constable got out of his cruiser and shoved him backward. Det. Sgt. Donovan told Constable Parker he was under arrest for assault. But the officer kept coming at him, he said, throwing “haymaker” punches.

       From there came the baton, and then all of a sudden the two officers had their guns drawn.

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       In all, Det. Sgt. Donovan fired 10 shots. Medical records for Constable Parker list gunshot wounds through his cheek and nose, left shoulder, upper thigh, left calf, left hip, lower abdomen, and right hindfoot. He was treated in hospital for two weeks, and required multiple surgeries after his discharge.

       This was the first time the two officers had ever worked together – though Det. Sgt. Donovan knew of the barrel-chested constable. In an interview with Ontario’s Special Investigations Unit after the shooting, Det. Sgt. Donovan spoke of the constable’s “violent past” with the police force, and his reputation as a “bully.” He’d heard from colleagues, he told them, that the constable used steroids.

       During his cross-examination of the sergeant, defence lawyer Joseph Markson argued these preconceived notions led the sergeant to be less than courteous with his client from the get-go that morning.

       “You were unhappy with Parker, and that it was Officer Parker who’d been assigned to the barricade, from the very start,” Mr. Markson said.

       Det. Sgt. Donovan disagreed.

       Though the two officers were alone at the time of the shooting, court heard Wednesday about the flurry of activity that soon followed.

       One of the first people to arrive was a civilian – by chance, a nurse practitioner – who tended to Constable Parker on the ground, while they awaited the ambulance.

       When one of the collision reconstruction officers rushed to the intersection, Det. Sgt. Donovan had him document various pieces of scattered evidence on the roadway, including a lanyard that had fallen from his neck, and Constable Parker’s baton.

       A man on the lawn of a nearby home also asked if he could help. Det. Sgt. Donovan asked if he had video. When he said he didn’t, he told him to stay there as a witness.

       Finally, the emergency task force arrived, and Det. Sgt. Donovan surrendered his holster and gun. Two officers then escorted him to a police cruiser, where he asked one of them to call his superiors and his wife. There in the passenger seat of the car, he said, he finally started to cry.

       “I realized that I could have been killed,” he said. “And I just broke down.”

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