The young man accused of murdering a 性视界传媒 teenager on a bus last year was "very badly bullied physically and emotionally" in elementary school, a judge heard during an ongoing trial Monday.

Kaiden Mintenko, 21, of Burnaby pleaded not guilty to second-degree murder in the April 11, 2023 stabbing of a 17-year-old boy on a 性视界传媒 bus, at the outset of the 15-day trial that began Dec. 2 with Justice Terry Schultes presiding, in B.C. Supreme Court in New Westminster.

The victim was stabbed in the right upper chest while riding on a Route 503 bus in the 9900-block of King George Boulevard and died in hospital. Schultes imposed publication bans on information that would identify the teen and two Crown witnesses. He also ordered a temporary publication ban on the identity of a fourth person. 

After the Crown closed its case Monday the defence called Dr. David Morgan, a forensic psychiatrist, to testify. Morgan said that while Mintenko "does not suffer from a psychotic disorder," he responds with violence when upset. He interviewed him in July.

He said Mintenko was exposed to "pre-natal intoxicants" like methamphetamine. Exposure to these can have a "markedly deleterious affect on the developing fetus and can lead to a wide variety of difficulties with cognition and other higher functions," Morgan told the court. He was born in jail. "His mother was in a very difficult position when she gave birth to him."

"He was very badly bullied physically and emotionally (in elementary school). He became very sad."

The court heard Mintenko was diagnosed with conduct disorder, which Morgan said involves breaching social norms "and the rights of others," as well as "serious rule-breaking."

In high school he got in with a crowd "who themselves have been rejected already. They're usually the peers who are in trouble with the law, abusing substances, not following the rules, that's the groups he fell in with and it gave him a sense of identity and he held onto that very, very tightly."

Morgan told the court Mintenko became fascinated with knives at a young age. When police searched his bedroom they found stab holes in his mattress and walls, the court heard.

"That bedroom wall was damaged badly by a bladed instrument," he said, "and the reason for that was Mr. Mintenko struggling to remain emotionally composed and not become angry."

The psychiatrist testified that Mintenko has difficulty managing emotions arising from frustration. "He does things on the spur of the moment," Morgan told the court, "and, you know, there's no thought."

"Mr. Mintenko isn't someone who thought through things." Morgan testified. "He acted on the spur of the moment, he acted impulsively."

"He's impulsive, and he's at risk of behaving recklessly," the psychiatrist told the court. He noted that Mintenko once picked up a kid and threw him in a lake.

"Again, picking up a child, and all he's done is call him a name. And the reaction you've got is consistent with that violence type picture. So he picks the kid up and throws him into the lake. There's no consideration as to whether the child can swim. And if he couldn't swim, now we've got a real problem. So it's the lack of forethought, and it seems to be a feature from his early childhood on."

"He's upset, and he responds with violence."

Morgan said Mintenko gets angry and can't control his temper. "That's the important point to take from this."

Last week, the trial heard that when police asked Mintenko what he would tell the teen's grieving mother, he replied "I f-ing killed him."

According to the Crown, at issue is whether Mintenko had a "specific intent" for murder. "As the court is aware, the Crown has to prove beyond a reasonable doubt that Mr. Mintenko intended to cause death or intended to cause bodily harm that he knew was likely to cause death and was reckless at to whether that ensued," Prosecutor Elise Kohno told Schultes.

Before the Crown closed its case, a forensic pathologist who has done 2,086 autopsies to date described in detail the fatal stab wound. Dr. Eric Bol did the autopsy in Burnaby Hospital's morgue on April 14, 2023, with Integrated Homicide Investigation Team police taking photographs.

Bol told the court a knife blade with a single edge was thrust 17 centimetres (6.69 inches) through the hardest bony part of the victim's third rib into his right lung, damaging the pulmonary artery and pulmonary vein. No life-saving measures caused his death, the pathologist confirmed.

"I determined the cause of death to be a stab wound of the chest," he said. "In this case two major blood vessels were injured."

Bol testified during cross-examination that he was unable to speak to the amount of force needed to pierce a rib bone.

"Not with any sort-of numerical value other than to say going through bone takes more force potentially than other substances in the body," he told the court.

Final submissions from the Crown and defence are expected to be heard Wednesday, after press time.