He may have been just a "lone wolf," working without links to any other radical groups, his deadly actions possibly motivated by Canada's involvement in the fight against ISIS.
But what's known for sure is that Martin Couture-Rouleau had been considered some kind of threat by the Canadian government.
And as details began to emerge about the 25-year-old, who had a pressure-washing business registered in Quebec, they began to paint a picture of a man who seemed to have embraced extremist ideas, and who, according to one friend, dreamed of dying as a martyr.
As Public Safety Minister Steve Blaney asserted at a morning news conference, Couture-Rouleau, who waited in a parking lot for at least two hours before driving his car into two Canadian soldiers, was “clearly linked to terrorist ideology.”
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The RCMP revealed that officials had been monitoring Couture-Rouleau closely, concerned that “he had become radicalized." On Tuesday, RCMP Commissioner Bob Paulson confirmed that Couture-Rouleau's passport had been seized and that he was one of the 90 suspected extremists who the RCMP believed intended to join militants fighting abroad.
And all of this has left his friends and family in shock. Gilles Rouleau, Martin's father, was in tears this morning when he spoke to Radio-Canada
'I lost my son'
“I lost my son, my son is everywhere [in the media] this morning. Leave me in peace. I have no comment."
Coutoure-Rouleau lived with his father in a St-Jean-sur-Richelieu white brick family home, where neighbours say they watched Couture-Rouleau change over the last year since his conversion to Islam.They say he grew a beard and stopped wearing jeans in favour of Islamic clothing.
CBC News spoke with Faisal, a Facebook friend of Couture-Rouleau’s in Saudi Arabia, who described Couture-Rouleau as a “really kind person."
He said he befriended Couture-Rouleau on Facebook and began messaging him in June.
"I was actually looking over some posts on Facebook ... and I saw all these people, they were for some reason dissing Islam, making fun of us, so I saw him actually replying in a really calm, modest, humble way," Faisal told CBC News.
But Faisal added that this was before he found out Couture-Rouleau was a supporter of ISIS.
Faisal, who spoke on the condition CBC News not publish his last name, said he changed the topic of conversation in the few instances Couture-Rouleau mentioned ISIS to him.
He referred to Couture-Rouleau as “Ahmad,” the name he adopted when he converted to Islam.
Faisal said he lived in Canada for a period of time, and did not agree with Couture-Rouleau when he allegedly called some members of Canada’s military personnel “infidels.”
Angry that Canada supported U.S. bombing of ISIS
"So he was really mad that Canada actually supported the American bombing of [ISIS] in Syria and Iraq so I think that was the main motive in killing that Canadian soldier."
Radio-Canada reported that Couture-Rouleau's Facebook page, which is no longer active, identifies him as Ahmad LeConverti (Ahmad the Converted). Legal documents show Couture-Rouleau converted to Islam in 2013
Propaganda videos and other materials admiring jihad — or “holy war” against enemies of Islam — were on his Facebook profile page, including a video featuring the logo for ISIS.
On a separate Facebook page, under the name Ahmad Rouleau, the profile picture had been changed last Friday to show a picture of two doors opening, one that appears to be leading to heaven, and one to hell.
Months earlier, on April 14, one of the posts reads: "Allah has promised the hypocrite men and hypocrite women and the disbelievers the fire of hell, wherein they will abide eternally. It is sufficient for them. And Allah has cursed them, and for them is an enduring punishment."
Underneath that post was the image of a sheik, combined with an Israeli and American flag and American dollar bill. It's one of a series of images critical of American foreign policy. The page also features links to anti-Semitic videos posted on YouTube.
On that Facebook page, Couture-Rouleau defends Islam, at one point writing "don't judge Islam by what other[s] do....study for yourself ... read the Qur'an."
According to information Radio-Canada obtained from a friend of Couture-Rouleau, he had convinced at least four or five people in his circle of friends to convert to Islam. But he said that Couture-Rouleau got carried away with an extreme interpretation of the Qur'an.
The friend said Couture-Rouleau spent hours on the internet and devoured jihadist literature, adding that Couture-Rouleau dreamed of dying as a martyr.
'Seems to be a lone wolf'
Dave Charland, a former intelligence officer with CSIS, said from the information he's gleaned so far about Couture-Rouleau, he believes Couture-Rouleau "seems to be a lone wolf" in part because of the lack of sophistication of the attack.
"Based on what's public right now, I don't think he had any links with any groups but clearly he had an extremist ideology. So he must have influences."
RCMP Commissioner Bob Paulson confirmed that Couture-Rouleau's passport had been seized and that he was one of 90 suspected extremists who the RCMP believed intended to join militants fighting abroad.