A Brampton, Ont., man has been charged with participating in the activity of a terrorist group after he was arrested by the RCMP on the weekend.

Kevin Omar Mohamed, a former University of Waterloo engineering student, allegedly travelled to Turkey on or around April 24, 2014 "to join Jabhat Al-Nusra," the RCMP Integrated National Security Enforcement Team said in a release.

He returned to Canada about a month later, on or about May 24, 2014, police said.

The RCMP began investigating in August 2015.

Jabhat Al-Nusra is listed by the Canadian government as being a terrorist organization. The Canadian Security Intelligence Service identifies it as the al-Qaeda affiliated Sunni militant Islamist group in Syria.

Mohamed was put under a "preventive" arrest by the RCMP on Saturday and was charged with possession and concealment of a weapon, a hunting knife.

Changing allegiances

Amarnath Amarasingam, a Dalhousie University professor and expert with the Canadian Network for Research on Terrorism, Security and Society (TSAS), said a University of Waterloo student caught their attention in 2015.

TSAS studies radicalization, monitors social media and consults with academics and policy-makers about security issues.

Amarasingam and his colleague Lorne Dawson, a University of Waterloo professor and the co-director of TSAS, said their research group became aware last year of a University of Waterloo student who went by the name Abu Jayyid after he made some online statements that appeared to support ISIS.

But in June 2015, they noticed Abu Jayyid stopped supporting ISIS on Twitter and instead, started to boost Jabhat al-Nusra.

This undated photo was Abu Jayyid's previous Twitter profile picture, according to Amarnath Amarasingam who exchanged messages with the account. (Twitter)

Dawson said this happened around the same time other fighters TSAS had been monitoring became alienated by ISIS and switched allegiance to other groups. This was likely why TSAS noticed a change in the Abu Jayyid tweets, he said.

"We didn't care about him. He was not someone we were focusing on, he was just another minor figure posting and making comments on jihadist material online, of which there are thousands in the world," Dawson told CBC News Tuesday.

Supporters: from naïve to defiant

Dawson said there are a number of reasons why someone might join an extremist group and leave it soon afterward. Sometimes it's due to pressure from families and friends to recant the new beliefs, but it can also be as simple as the person being needed at home to tend sick family members or friends.

He said in their research, they observe many people who take up the cause online, including using Twitter, Facebook and Kik.

There are two types, he said: the ones who don't realize that their thoughts and views could get them into serious trouble, and the ones who don't care.

"Part of them are just naïve and don't get it and don't understand and they, even in some of our interviews we have … people making comments that they just don't get the extent to which all of this activity may be being monitored," he said.

"Then there's another group that knows full well and they just don't give a damn. It's an act of defiance."

Active online

Abu Jayyid's Twitter account links to a website called ask-book.com, where users can pose questions to each other and get responses.

Nine months ago, Abu Jayyid was asked, "Do you support ISIS?"

"I don't support any particular group to be honest," was the reply.

He said "thank you" to one person who said he had a nice smile, confirmed he had been to Niagara Falls "when I was a lot younger" and explained to one person why Canadians sometimes buy their milk in bags.

But he also answered questions like, "Do you want to end this fitnah [conflict] between IS and Nusra?"

He replied, "I think if they can't stop fighting with the other groups (not just Nusra) then they should leave Syria … staying in Syria damaged the fight against [Syrian President] Bashar [al-Assad]."

For the most part, Dawson said, Jayyid appeared to be a supporter, not an instigator.

"The general trend for the group that he was affiliated with is to blame ISIS for having created dissention and discord amongst the jihadist cause," Dawson said.

"It's almost all in debates clarifying what is justified and what isn't justified, what is in accordance with proper Muslim principles or not and debates between people and adjudicating who's got it right," he added. "He was not engaged in saying, at least in his public Twitter ... fight the Canadian government."

Former student

In an emailed statement, University of Waterloo spokesman Nick Manning confirmed Mohamed attended the school.

"We can confirm Kevin Omar Mohamed is not a current student of the University of Waterloo and was last registered as an engineering student in the Spring term of 2015. He did not graduate," Manning said. "The University of Waterloo will cooperate with the RCMP, as needed."

Mohamed is being held in custody until a bail hearing, which is scheduled to take place over three days starting April 19, in Brampton.

Dawson noted that the RCMP said Mohamed did not pose any kind of domestic threat.