​Two months before killing six men inside a Quebec City mosque, Alexandre Bissonnette sat in the parking lot of a nearby shopping centre, debating whether he should go in and kill unsuspecting shoppers, then commit suicide, a Quebec City court heard Monday.

Marc-André Lamontagne, a psychologist who interviewed Bissonnette over two days earlier this month, told the court that Bissonnette was obsessed with the need to give a "a sense of grandeur" to his death after suffering through years of bullying and depression.

Bissonnette's increasing anxiety forced him to take a medical leave from work in November 2016.

Later that month, on Nov. 26, 2016, Bissonnette drove to Place Laurier, one of the city's most popular shopping centres, armed with two pistols and 50 bullets.

"He was juggling with the idea of committing suicide or killing people inside the shopping centre," said Lamontagne.

After drinking alcohol in the underground parking lot, he finally entered the shopping centre and sat down to drink coffee, his guns still stored away in his backpack, Lamontagne's expert report shows.

At that point, Bissonnette had decided not to go ahead with his plan, but he became convinced surveillance cameras had captured him loading his gun and that he was going to be arrested.

That's when Bissonnette turned his attention to the mosque on Chemin Ste-Foy in Quebec City, Lamontagne said.

The expert said Bissonnette rationalized that his new target "would be more acceptable in his eyes and in the eyes of others," and he became convinced in the days prior to the shooting that there were religious extremists inside the mosque.

"If there were one, two, three religious fanatics, I would have eliminated them," Bissonnette told Lamontagne.

Sentencing hearings for Alexandre Bissonnette continue this week following victim impact statements. (Jacques Boissinot/The Canadian Press)

Bissonnette, 28, pleaded guilty in March to six first-degree murder charges, in addition to six counts of attempted murder, after the mosque shooting on Jan. 29, 2017.

Quebec Superior Court Justice François Huo​t must decide if Bissonnette's periods of parole eligibility will be consecutive or concurrent.

If they are consecutive, he would theoretically have to spend 150 years in prison before being eligible for parole — 25 years for each count of first-degree murder.

His legal team is hoping it will be concurrent, which would make him eligible to apply for parole after 25 years.

Escalating anxiety

Lamontagne, who assesses the potential risk dangerous convicts pose for reoffending, said Bissonnette had struggled with suicidal thoughts since adolescence, when he was bullied by classmates, but "the downward spiral started during the spring of 2014."

Relying on his own interviews and on Bissonnette's extensive medical records, Lamontagne laid out how the young man had become absorbed by Elliot Rodger, who killed six people outside a university campus in Isla Vista, Calif., in May 2014.

"He started to have this fantasy that he could commit suicide and go back in time, to prevent this drama from happening," Lamontagne explained.

Once he was ready to carry out his plan, Bissonnette told Lamontagne, he realized the people who had bullied him during his adolescence would have another reason to laugh at him if he killed himself.

"That's when he said he came up with the idea of killing people before committing suicide," Lamontagne said.

'Moderate risk' of reoffending, expert says

Described as a "fragile narcissist," Bissonnette suffered from low self-esteem and depression, but also maintained a sentiment of greatness, Lamontagne said.

"He absolutely wanted to prove he is special," he told the court.

In Lamontagne's expert opinion, Bissonnette was more interested in the suffering he shared in common with other mass killers, rather than their ideologies.

A search of Bissonnette's computer revealed he had done extensive research on Dylann Roof, a white supremacist, as well as other mass murderers.

The psychologist said Bissonnette's desired to commit an act of violence more than express political views.

"He wanted to kill anybody," Lamontagne said, settling on a target he considered would be "more acceptable."

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Based on similar psychiatric evaluations, Lamontagne said, he believes Bissonnette would pose a "moderate threat" if he were allowed to ask for parole after 25 years.

By then, Bissonnette at age 53 could potentially be rehabilitated, "but if he does reoffend, [the crime] could be serious," he said.

The Crown will begin its counter-interrogation of Lamontagne Tuesday morning.

Bullied as a teen

Earlier Monday, Bissonnette's high school French teacher, Lucie Côté, described Bissonnette as a lonely teenager who was bullied by his classmates "on a daily basis."

Côté said that when she saw the face of her former student on television, the day after his arrest, she started crying.

Lucie Côté, Alexandre Bissonnette's high school teacher, testified for the defence during sentencing Monday in Quebec City. (CBC)

"I couldn't believe it," said Côté, 71, who told the court she reached out to the legal aid team representing Bissonnette because a voice kept telling her, "I could have done more."

Côté said she witnessed the bullying in two different schools Bissonnette attended, in both Grade 8 and Grade 10. She said he was tripped in the hallway and constantly taunted inside her classroom.

She called on Huo​t to have mercy on her former student.

"I'm asking you to leave him hope, which will allow him to work on his rehabilitation," Côté said.

Dozens of people testified last week for the Crown, asking Huot to give Bissonnette the most severe sentence possible.

Families of the victims also shared how they were fearful they'd have to one day live in the same city as Bissonnette.