A jury is deliberating the fate of a Hamilton-area homeowner charged with second-degree murder in the shooting of a man who broke into his truck.

Peter Khill, 28, admits he killed Jon Styres with two shotgun blasts in the early morning hours of Feb. 4, 2016, but says he fired in self-defence, believing Styres was about to shoot him.

Styres, a 29-year-old father of two from Ohsweken, Ont., on the Six Nations reserve, did not have a gun at the time of the shooting, but the jury can rule in Khill's favour if they decide he "reasonably" believed he was under threat, Superior Court Justice Stephen Glithero told its members Tuesday morning.

"In some circumstances, our law allows a person to do things that would otherwise be unlawful, to defend or protect themselves or another person from the actual or threatened use of force," Glithero said.

Khill and his girlfriend awoke to the sound of banging outside their rural home on the morning of the shooting, and saw Styres inside their truck parked outside, the jury was told during the trial. Khill loaded his shotgun, left the home through the back door, and cut through a breezeway between the house and the garage to confront Styres.

The Crown has argued that Styres did not pose a reasonable threat to Khill and his girlfriend while they were inside their locked home, and that Khill should have called 911 and waited for police rather than run out of the house with a loaded shotgun.

The defence has said Khill spent four years as an army reservist, and instinctively fell back on his military training to "neutralize the threat" when he saw a strange man on his property.

The onus is on the Crown to prove beyond a reasonable doubt that Khill was not acting lawfully in self-defence, rather than Khill having to prove he was justified in his actions, the judge said.

To decide that Khill acted in self-defence, jurors must answer yes to three questions, the judge said: Did Khill reasonably believe force was being used or threatened against him? Was his purpose in shooting Styres to defend or protect himself -- as opposed to getting revenge or to exact punishment, for instance? And was Khill's conduct in shooting Styres a reasonable response to the perceived threat, under the circumstances?

If jurors decide Khill was not acting in self-defence, they must then decide whether he is guilty of second-degree murder or the "lesser included charge" of manslaughter, Glithero said.

The jury can return a verdict of murder if they determine that Khill intended to kill Styres or to do him bodily harm that he knew was serious or dangerous enough to kill him.

If they decide Khill did not intend to kill Styres, they can rule it was manslaughter.

Glithero reminded the jury that, during the trial, Khill testified that he did not intend to cause Styres' death, but that he did intend to cause him harm, and understood that doing that harm could kill him.