Peter Khill told the jury at his second-degree murder trial on Tuesday that he was acting in self-defence when he fired two shotgun blasts at a man in his driveway.

When Mr. Khill discovered that his pickup truck was being broken into on Feb. 4, 2016 – a commotion that woke him and his girlfriend around 3 a.m. – he did not call 911.

He did not flick on the porch light, or shout from the front door to scare off whoever was there.

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Instead, the then-26-year-old fetched his shotgun from his bedroom closet, loaded it and headed out the back door. Barefoot, in just his T-shirt and boxers, he trekked quietly through the breezeway between his house and garage out to the driveway, where, in the pitch black, he could see a figure leaning into the passenger side of truck.

“Hey, hands up,” Mr. Khill said he yelled at the thief – a shout he demonstrated at full volume in the courtroom on Tuesday.

When Jonathan Styres turned, raising his hands toward him, Mr. Khill fired twice. Both shots struck the 29-year-old father of two from Ohsweken, Ont., on the Six Nations reserve; once in his chest, and once in the back of his right shoulder. He died almost instantly, his body lying face-up in Mr. Khill’s muddy driveway.

The case has been compared to the trial of Gerald Stanley, a Saskatchewan farmer who was acquitted in February of the fatal point-blank shooting of Colten Boushie, a Cree man.

Mr. Khill – who has pleaded not guilty – does not deny he killed Mr. Styres. The jury’s job will be to decide whether he did so intentionally.

In his opening address on Tuesday, after a week of Crown evidence, Mr. Khill’s lawyer, Jeffrey Manishen, laid out the thrust of his client’s position: “This is a case about self-defence.”

Mr. Khill, he argued, was following the training he received during his years as a part-time military reservist, from 2007 to 2011.

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His instructor and direct superior from that time, Walter Sroka, was the first witness called by the defence on Tuesday.

“The training is based on repetition,” Mr. Sroka, who now works in wind-turbine construction, explained to the jury. “You do it so much that you don’t have to think about what you’re doing.”

Soldiers are trained to respond pro-actively, rather than reactively, to threats. But unlike in the movies – which Mr. Sroka noted often depict soldiers as “gung-ho and aggressive” – he stressed that Canadian soldiers are trained to be respectful.

In cross-examination, assistant Crown attorney Steve O’Brien pointed out the difference between the “theatre of war” and day-to-day civilian life.

“No Canadian soldier is ever trained or told that their training immunizes them from the use of common sense or obedience to criminal law?” Mr. O’Brien asked.

“That is correct,” Mr. Sroka replied.

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“The rules of engagement are … a kind of code for soldiers in a theatre of war, or [during] an operation … they do not supersede what you’re allowed to do in a civilian context?”

“Correct.”

In his own testimony, Mr. Khill argued there is overlap. He was afraid for his life that morning, he argued – and for the life of his girlfriend, Melinda Benko (now his pregnant wife).

“I felt that I was being threatened, and I wasn’t in control of the situation,” he said, referencing a garage door opener in the truck that could have provided a thief access to the home.

“I didn’t know how many people were out there, what they wanted or where they were … I needed to gain control of the situation and neutralize any threat,” he said.

His goal was textbook: Challenge. Disarm. Detain. Then, he said, he would have called police.

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But Mr. O’Brien put to him that the “obviously reasonable thing to do” would have been for Mr. Khill or Ms. Benko to call the police in the first place, from inside the house.

Mr. Khill argued that his response was reasonable also.

“This could’ve been some goofy teenaged kid – not an armed Taliban insurgent, some kid from your neighbourhood. And it wasn’t worth a moment’s call to 911?” Mr. O’Brien asked.

“There was a threat outside, and I felt like I needed to neutralize it,” Mr. Khill replied.

“There was a guy stealing your truck outside. And you killed him. It was not a threat that you neutralized. It was a human being that you struck twice and killed.”

Although Mr. Khill said he thought the man was pointing a gun at him, he was unclear on Tuesday about just how high the man’s hands were before he fired.

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“I wasn’t going to wait until there was a bullet in my chest,” he said.

The trial will continue on Wednesday with legal arguments. The jury will return on Thursday.