Two years before the deadly al-Qaeda linked attack on an Algerian refinery, one of the two Canadian militants who participated in the assault made a farewell tour of London, Ont., and said goodbye to those he knew, CBC News has learned, as more details emerge about the young men.

Where Ali Medlej disappeared to before the deadly attack in January and how he may have been trained to participate in it are not yet known, but CBC News has learned that Medlej and fellow militant Xris Katsiroubas had been searching for a radical path, something they didn’t find in their city’s main mosque or at a youth centre.

One of Medlej’s friends remembers a disturbing conversation with him, in which he said he was wrestling with a spiritual pursuit, but didn’t want to give up girls or drinking. He said Ali told him, "There's things that I just can't give up on in my lifestyle, and it's hard for me to be a practising Muslim, so why don't I just be a shaheed [martyr] and go straight to heaven instead of all the effort that I can't seem to do."

A third man, Aaron Yoon, travelled to North Africa with Medlej and Katsiroubas before the attack but did not participate in it. CBC News has confirmed that Aaron Yoon is in jail in the Islamic Republic of Mauritania in North Africa. Foreign Affairs confirms it is aware of this.

Like the others, Yoon was a student at London South Secondary School. He had been raised a Catholic, but converted to Islam, as did Katsiroubas, who had been Greek Orthodox, and along with Medlej they were given space at the school to perform prayers.

A former colleague, who asked not to be named, worked with Yoon in 2008 and then again in 2011, said she noticed a drastic change in his demeanour over that time.

"He just didn’t have that spark. He wasn’t that friendly, outgoing guy anymore. He just seemed lost and kind of dead inside," she said.

"He had a lot of friends, He was very sociable. But then he just didn’t want to talk to anyone. He didn’t open up to anyone. It was just him and his religion and his job. That's it."

How the young Canadians became involved in the attack in Algeria is not yet clear, but the CBC’s Greg Weston reports that sources suggest they were influenced by one man operating in southwestern Ontario.