But a series of surveillance camera videos played for a coroner's inquest on Tuesday showed that when a police officer boarded the bus, the situation escalated abruptly.
Jardine-Douglas, 25, is seen first trying unsuccessfully to push open the rear doors of the bus, which don't budge. The young man in a red and black baseball cap then reaches into his backpack, pulls out a knife and walks towards the officer.
"The officer started to run backwards...He was saying 'drop that knife, drop the knife,'" bus driver Ralph Charles recounted on the witness stand. "When (Jardine-Douglas) passed towards me I saw something silver in his hand."
The inquest is examining the deaths of Jardine-Douglas, Sylvia Klibingaitis and Michael Eligon, who were all holding sharp items and experiencing mental health issues when they were gunned down by police.
The province's police watchdog cleared authorities of wrongdoing in all three cases, prompting calls for justice from the families of those killed.
In Jardine-Douglas's case, his sister had called 911 for help dealing with her agitated brother in August 2010.
"My brother is a little bit mentally disturbed right now," she had told the operator. "He's not well."
The inquest heard how Jardine-Douglas calmly paid his fare and boarded Charles's bus while the young man's sister was still on the phone with authorities, giving them details on how to find him.
Once Jardine-Douglas had drawn his knife, Charles said the officer got off the bus, drew his firearm and backed into a nearby fence while the young man kept advancing.
In a matter of seconds, two to three shots were fired and Jardine-Douglas "went down" but tried to keep going until another shot was fired and he collapsed completely, said Charles.
"When I put myself into the position of the family members, of the parents, it's hard, because I have kids, and I always tell them I would prefer to die first," said Charles, who grew emotional on the witness stand. "But I know as well how the officer feels."
Blythe Brett, who was passing the scene in a car at the time, told the inquest she was convinced Jardine-Douglas was going to hurt someone.
"It was the man's demeanour and his facial expression. It wasn't like he was scared or trying to find a way out," she said. "Either he was on drugs or that he had had some kind of psychotic break. It didn't make sense, the actions he was making."
Brett said it seemed like Jardine-Douglas had "honed in" on the officer.
"The police officer was either going to get hurt or he was going to shoot the man," she said.
Meanwhile, Elizabeth Phillips, who saw the scene play out from her apartment balcony, said while Jardine-Douglas didn't appear to have the knife raised above his head, he wouldn't stop moving towards the officer who was yelling at him to "get down, lie down."
"He was very determined," she said. "He was leaning forward, much like he was going to head-butt the officer."
Jardine-Douglas's parents sat through Tuesday's testimony with serious expressions, frowning at times as videos played and witnesses recounted their memories of the incident.
"They're devastated by the way this matter was handled....(Jardine-Douglas) was very quiet, he was never abusive to anyone physically, he sort of kept to himself and he basically was always trying to avoid people, not to confront," family lawyer John Weingust said outside the inquest.
"They feel they can't do much in regard to their son, he's gone. But...something has to be done so it doesn't happen again."
Weingust said Jardine-Douglas's family hopes the inquest will result in recommendations that police officers use special procedures when confronting people they know to be mentally unstable.
The inquest has already heard from a police instructor who said officers' reactions are based on a person's behaviour and not on their mental state, testimony Weingust said Jardine-Douglas's family had found concerning.
"There has to be better training, better understanding," he said. "This was a mere situation where the (family) had called the police saying 'Will you help me bring back my son.'"
The inquest's jury may make recommendations at preventing similar deaths but is not tasked with finding fault or laying any blame