Islamic State militants have claimed responsibility for the attack in Dhaka, but authorities are still investigating who led the hostage-taking that resulted in at least 20 deaths.

One of the likely suspects: a terrorist group in Bangladesh that is affiliated with IS and is reportedly led by a Canadian.

Tamim Chowdhury, who goes by Shaykh Abu Ibrahim al-Hanif, is a Bangladeshi-Canadian who is leading a militant arm with close ties to Islamic State, according to the Bangladeshi newspaper The Daily Star.

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Mr. Chowdhury is also connected with an IS study group, which cited him as the leader of the Bangladeshi IS effort. In the April issue of Daqbi, a glossy magazine published by Islamic State, Mr. Chowdhury called for a united country free of "deviant sects, who are busy misleading the masses." The magazine identified Mr. Chowdhury as the "emir," or ruler, of its Bangladesh branch.

"I know that he's from Windsor," said Amarnath Amarasingam, a post-doctoral fellow in the Resilience Research Centre at Dalhousie University who specializes in radicalization and terrorism. "I know he's the head of the ISIS group, or at least a pro-ISIS group, in Bangladesh."

Mr. Amarasingam said Mr. Chowdhury's name came up repeatedly during his research in the community. "There were a few [people] who knew him from the mosque and from the social circles," Mr. Amarasingam said. "He was a shy, skinny kid."

The Windsor Islamic Association, in a statement on its website from last month, said it has not received official confirmation of Mr. Chowdhury's identity as head of the Bangladeshi group.

Mr. Amarasingam said while Mr. Chowdhury lived in Windsor, it was unclear if he is a Canadian citizen or when he left the country.

Public Safety Canada declined to comment on Mr. Chowdhury, but said the government is "taking every step to identify terrorists and prevent their activities."

The attack on the Holey Artisan Bakery in Bangladesh's diplomatic zone killed 20 people, including foreigners from Italy, Japan and the United States. IS said it targeted the citizens of "Crusader countries" in the attack.

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Canada's foreign affairs office said it is working with consular officials in Dhaka to determine whether the hostage crisis has "directly affected" any Canadian citizens.

With a report from Associated Press