Three days before Martin Couture-Rouleau drove his car into two Canadian soldiers, killing one and injuring the other, he posted an image to his Facebook page showing two doorways.

The left door opened to heaven, the right door led to hell.

It was the latest disturbing image he had posted to promote a perverted version of Islam that family, friends and law-enforcement officials had tried to pull him away from.

Couture-Rouleau’s disturbing online activity can be traced back to at least last spring.

On May 27, 2013, Couture-Rouleau -- under the name Ahmad Couture-Rouleau -- posted comments on an online Time magazine story on assaults within the U.S. military. Most are links to YouTube videos, including an anti-Semitic video on the Talmud and its “darkside of secrets,” but he also wrote a comment.

“Islam is the only true religion. anyone who want scientific proof of god that your terrorist zionism rothschild media hide, contact me or add me if you re open minded,” he wrote.

Couture-Rouleau’s online activity first caught the eye of the RCMP last June. It was also seen by Lorne Dawson, a University of Waterloo professor who studies radicalization and terrorist recruitment.

“My research group was following Couture-Rouleau’s activity online, so lots of people in Canada were aware of him. But he looked very amateurish; he didn’t look like he was a serious threat,” he told CTV’s Power Play.

Dawson said Couture-Rouleau fit the profile of a potential “lone wolf” terrorist who becomes radicalized on his own, unlike the young men from Calgary who travelled to Syria to fight for the Islamic State.

“His Islam may have been just a stepping stone on his way to achieving a radical identity -- that was probably his primary objective, and that probably grew out of various frustrations in his life,” Dawson said.

“Lone wolf terrorists are much more likely to be suffering from some kind of psychological difficulties and struggle,” he added.

RCMP officers met Couture-Rouleau in July, after he expressed a desire to leave Canada. Officials confiscated his passport but decided there wasn’t enough evidence to charge him with a crime.

“We could not arrest someone for having radical thoughts,” said RCMP Supt. Martine Fontaine.

In an attempt to de-radicalize Couture-Rouleau, law enforcement officials continued to meet with him, right up until Oct. 9 -- just 11 days before his violent hit-and-run attack on two Canadian soldiers.

On Tuesday, Mounties said there was nothing to indicate Couture-Rouleau was about to commit an act of terrorism.

Dawson said Couture-Rouleau was likely set off by some sort of trigger, which would have been very difficult to predict.

“The nature of his crime looks like it was very opportunistic,” Dawson said. “I suspect it wasn’t very well planned. He clearly didn’t have an escape route. He didn’t intend to become a martyr, unlike others, like those (who killed) the British soldier in London -- they stood and waited for the police to arrest them so they could give testimony to their act.”