Abu Muslim, who used to be known in Timmins, Ont., as Andre Poulin, arrived in Syria in late 2012 and died last August in an attack by Islamist groups on a government-held airfield.
Another young Canadian man who converted to Islam and was radicalized has been confirmed dead after fighting in Syria, a CBC News investigation has learned.
By the time of his death in Syria, Andre Poulin from Timmins, Ont., had become a battle-hardened jihadi known as Abu Muslim.
He arrived in Syria in late 2012, and joined a unit of foreign fighters controlled by a Chechen.
He spoke freely with an American filmmaker last spring about what his family thought of what he was doing in Syria.
"Well, on the one hand, they are happy I have found my path and doing my own thing, you know, helping people, but at the same time they don't understand entirely why I am here," he said in a Channel 4 documentary.
Last August, he was part of an attack along with other Islamist groups on a government-controlled airport in the country's north.
He died in the attack, and his body was found and buried by other jihadis.
He is said to have left behind a wife and young child in Syria.
In Timmins, from 2008 to 2009, when he was barely 20 years old, the young man was already on the path toward a strict interpretation of Islam. He worried about how he was dressing and how others around him behaved. His language also started to change and harden, said CBC's Adrienne Arsenault.
He developed a separate identity, calling himself Uncle Umar. His Arabic signature read: "Martyrdom, if God wills it."
He posted thousands of messages on the internet, asking for, and offering, advice. He told stories of his life, his apparent marriage and troubles. In 2009, he talked of just getting out of jail on accusations of terrorism.
Some posters on internet forums he frequented referenced his passport being taken away, Arsenault said.
He also wrote of people in his hometown being afraid of him, and of police watching his every move.
He had a criminal record for uttering death threats, theft, harassment and carrying a weapon.
Online, he wrote that he'd been accused of threatening to blow up a Timmins gas station.
Filmmaker Bilal Abdul Kareem told CBC News that his clearest memory of the man from northern Ontario is of someone unwavering in determination but with home always on his mind.
"One time, he was out for a long time out on an operation, and he was keen to find a phone so he could call home and find out how his little brothers are doing," Kareem said. "So that was the Abu Muslim I knew."
On Wednesday, Arsenault reported on the death of Mustafa al-Gharib, a 22-year-old who was born in Nova Scotia as Damian Clairmont. He left Calgary for Syria in November 2012 and was killed just days ago by Free Syrian Army (FSA) forces.
It is unclear how many Canadians are fighting in the Syrian civil war, but estimates range from a dozen to more than 100.