Forensic psychiatrist testifies in final day of evidence in Peter Khill murder trial

When faced with a potentially dangerous situation, human instinct kicks in.

The central command" brain begins to send signals to other parts of the body, which can increase adrenalin, raise heart rate, narrow vision and inhibit rational decision-making - an automatic reaction" that sets in before the person is even consciously aware of it," testified forensic psychiatrist Peter Collins.

The psychiatrist is the final witness in the second-degree murder trial for Peter Khill. Khill is charged in the death of Jonathan Styres, 29, who was killed after being shot in the chest and right shoulder on Feb. 4, 2016, and has pleaded not guilty.

Khill previously testified he feared for his safety the night he fatally shot Styres, an Indigenous man who lived on Six Nations who was allegedly trying to steal Khill's GMC pickup truck from the rural Binbrook driveway.

The accused previously testified that his response was that of a soldier, which is how he was trained.

Collins, who has worked with several police services in Canada and was in Afghanistan twice, said people typically fight or flee - or sometimes freeze - when confronted with stress. But skills acquired in training, such as for policing and military, have the capacity to moderate the response," causing them to think through" potentially dangerous situations, he told defence lawyer Jeffrey Manishen.

They're potentially calmer and more able to make an assessment in a dangerous situation than someone who didn't have that type of training," Collins said.

During cross-examination, assistant Crown attorney Paul McDermott suggested to Collins someone could ignore all or parts of their training and act independently.

There's still free will," Collins agreed. But generally people fall back on their training because that, in a sense, becomes their comfort zone."

The Crown previously suggested Khill acted on emotion - anger - not self-defence when he killed Styres.

Ladies and gentlemen, that is the evidence in this case," Justice Andrew Goodman told the jury as Collins' testimony concluded. We're getting to the finish line but we're not quite there yet."

Jurors - now 12 after one juror was discharged Monday after becoming ill - return Wednesday for closing arguments.

Kate McCullough is an education reporter at The Spectator. kmccullough@thespec.com