He faces six counts of first-degree murder and five attempted murder charges, according to the Royal Canadian Mounted Police in Quebec.
Bissonnette, a student at Laval University, lived in an apartment a few miles away from the mosque.
A Facebook group dedicated to welcoming refugees in Quebec City said Bissonnette was known online for making statements inspired by extreme right-wing French nationalists.
Suspect was unknown to police
He was a student at Laval University in Quebec City, according to the school. Bissonnette worked in a call center located at the university for Héma-Québec, a non-profit that manages blood donations in the province, according to the organization’s spokesman Laurent Paul Menord. Héma-Québec said in a press release that it was “shocked” to learn that Bissonnette was an employee.
Neighbors told CBC Bissonnette rented an apartment with his twin brother near the mosque. He was unknown to police and had not been on any watch lists, authorities said.
Bissonnette’s friends told The Globe and Mail newspaper that he became interested in politics after Le Pen visited Quebec City in March.
The paper quoted a friend, a fellow student at Laval University, who knew Bissonnette from childhood and was friends with him on Facebook.
‘Wrote him off as a xenophobe’
“I wrote him off as a xenophobe,” Boissoneault told the newspaper. “I didn’t even think of him as totally racist, but he was enthralled by a borderline racist nationalist movement.”
François Deschamps, an employment counselor who runs a refugee support Facebook page, told the paper he recognized Bissonnette’s photo from his frequent appearances online, including on the page he administers.
“He was someone who made frequent extreme comments in social media denigrating refugees and feminism,” Deschamps told The Globe and Mail. “It wasn’t outright hate, rather part of this new nationalist conservative identity movement that is more intolerant than hateful.”
Another Laval student, who asked not to be identified, told CNN he was in a political science course with Bissonnette.
“I was shocked when I saw his face on the media, because I recognized him immediately,” the student said.
Bissonnette “didn’t bring a notebook, just his computer. I think he was a gamer type,” the student said, adding that he seemed to have few friends.
“No one really knew him,” he said.
Man also identified as a gunman was trying to help
Bissonnette made a brief court appearance Monday. He will remain in custody until his next court appearance, set for February 21.
Authorities have not named a possible motive, but Canadian Prime Minister Justin Trudeau denounced the attack as an act of terrorism.
Police initially said two gunmen attacked the mosque but later concluded that the second person was a witness.
That man, Mohamed Belkhadir was arrested and later released by police after a witness mistakenly identified him as a suspect.
“I was outside the mosque…then I went inside to see if my brothers were okay…I found one of them near the door,” he told the network in French. “I wasn’t sure if he was alive or dead. I saw someone else who was still breathing and I gave him my coat. At the moment, I saw the shadow of someone carrying a gun…and I didn’t realize it was a police officer.”
CNN’s Julia Jones, Darran Simon, Deb Feyerick, Ann Roche, Chris Boyette and Tanika Gray contributed to this report.