The man charged with killing a woman by lighting her on fire on a TTC bus two years ago admitted to causing her death, but should not be found criminally responsible due a diagnosis of schizophrenia, prosecutors and defence counsel argued at the outset of his trial in Toronto.

Led into the courtrooms in handcuffs on Monday morning, Tenzin Norbu pleaded not guilty to the charge of first-degree murder in front of Superior Court Justice Maureen Forestell, presiding over the matter without a jury. Norbu was arrested and charged with the attempted murder of Nyima Dolma in June 2022, shortly after he lit her on fire aboard a bus at Kipling Station in west Toronto.

Dolma and Norbu were strangers to one another at the time of the offence.

According to an agreed statement of facts, Dolma, on her way to work as a caregiver, was sitting near the back of the bus when Norbu boarded and stood behind her. In an interaction that lasted minutes, Norbu, who immigrated to Canada in 2008, asked the woman if she was Tibetan before removing a mason jar of lighter fluid from his backpack, dousing her in it, and igniting the substance, the court heard during the Crowns opening statements. She suffered burns to 60 per cent of her body, covering her face, neck, arms, and legs.

The incident was captured in its entirery on TTC surveillance footage but was not tendered as evidence in the case to protect against further collateral trauma.

After 18 days in hospital, Dolma died on July 5, 2022. She was 28 years old. At that time, police upgraded Norbus charge to first-degree murder.

On Monday, both Crown prosecutors and Norbu’s lawyers asked Justice Forestell to find him not criminally responsible for Dolma’s death, arguing that a “long-standing” psychotic state rendered him incapable of fully understanding what he’d done.

Alina Iosif, a forensic psychiatrist who reviewed years worth of Norbu’s medical records before assessing him, told the court she believed he suffered from schizophrenia when he attacked Dolma, and that he had displayed psychotic behaviour for nearly a decade prior to the offence. Norbu had likely been misdiagnosed with depression years earlier and was medicated as such, she said.

Norbu’s delusions, Iosif testified, included ongoing preoccupations with Tibetan politics, fire, and his sexuality, and, on several occasions, he revealed to doctors a desire to light himself on fire, she said.

“I see these themes as almost obsessional,” she testified. “The cornerstone of these themes is anchored in psychosis.”

Lawyers for Norbu did not call any evidence following Iosif’s testimony but made a joint submission that their client be found not criminally responsible.

“Mr. Norbu suffered from a longstanding diagnosis of schizophrenia,” Crown attorney Brady Donohue told the court. “There is clear evidence that he was delusional, psychotic, disorganized and for that reason, he could not understand that his act was wrong.”

In a prepared statement read out loud to the court, Dolma’s sister called the day of the attack “the darkest day of her life.”

“She had a whole life ahead of her,” she said. “I can’t put into words the pain, suffering, trauma I had to go through.”

TTC Supervisor Cameron Jackson, who tried to help Dolma after she ran from the bus and onto the Kipling platform, also gave a statement in which he said the incident still serves as a “stark reminder of the fragility of life.”

“Every interaction is tinged with a sense of detachment,” Jackson said from the witness stand. “As I grapple with the barrage of memories, I replay every moment of the incident in a desperate attempt to decipher what I could have done differently.”

Justice Forestell is scheduled to hand down her decision on Tuesday.