During high school, Ali Medlej was considered a "happy-go-lucky" football player. Xristos Katsiroubas, his classmate, was a quiet student from a Greek Orthodox family.
The two twentysomething Canadians are now dead and implicated in an al-Qaeda-inspired conspiracy that killed dozens of innocent Westerners at a gas complex in the Sahara Desert.
How they journeyed from a Southwestern Ontario city to the front lines of an attack that shook the world has not been revealed. But federal security officials have openly dreaded just such a "homegrown" terrorist event for more than a decade – arguing that it was always a question of when, and not if, a Canadian radical would commit a massacre.
This fear now has proof and human faces. Canadian police and intelligence officials have been to Algeria in recent weeks, obtaining DNA that confirms the Canadians' involvement.
Security officials won't officially comment on the identities, but the names of Mr. Medlej and Mr. Katsiroubas were revealed by the CBC this week.
Now the RCMP and the Canadian Security Intelligence Service are trying to figure out who the men's accomplices were, even as they retrace past investigations. Years before, the two men had been red-flagged by authorities as potential threats to Canada, along with members of their wider circle.
Federal politicians are already contemplating stepping up security practices. "Obviously my colleagues and I will be discussing this in the days and weeks ahead," Canada's Foreign Minister John Baird told reporters in the United Arab Emirates on Tuesday.
During a four-day siege of the remote In Amenas gas complex in Algeria last January, an Islamist faction known as "Signatories in Blood" killed 38 Westerners it had taken hostage. The al-Qaeda-aligned leaders of the group boasted during the standoff that two Canadians were part of their faction.
When the Algerian army attacked, many of the 29 terrorists who eventually died had blown themselves up with their prisoners.
Mr. Medlej and Mr. Katsiroubas had been friends at the London South Collegiate Institute in London, Ont., a mid-sized city two hours west of Toronto.
"In my memory, he's got a smile and was kind of a happy-go-lucky person," said former classmate Michael Melito, 25, who was shocked to hear the news. "I don't know how he's changed or who he met since high school …"
Mr. Katsiroubas came from a Greek Orthodox family with roots in London, Ont.
"It's very bad … the whole family is in mourning," the young man's uncle, Gus Katsiroumbas, said when reached Tuesday. He wouldn't elaborate about his nephew's history. "I don't know myself," he said. "We'll wait and see."
Late Tuesday, the CBC reported that a third man named Aaron Yoon, a Canadian of Korean descent who had converted to Islam while attending high school with the other men, travelled to Algeria along with the others. He has been reported to be in a North African jail after being arrested under mysterious circumstances sometime before the attack. There is no evidence to prove that he participated in planning the attack, and the details of the CBC report could not be confirmed. The man's family denies he has links to terrorism and doesn't believe he's in jail, the CBC reported.
The CBC also reported that Mr. Medlej and Mr. Katsiroubas moved together to south Edmonton in early 2007.
"Ali was a smooth talker. He was definitely the leader. Xris was quiet," their landlord was quoted as saying. The CBC reported that Mr. Medlej was fined $500 after pleading guilty to shoplifting groceries that March and that they were evicted for damaging their apartment.
It was around this time that the pair, as well as members of their wider circle, first appears to have fallen under scrutiny by the Canadian Security Intelligence Service – an agency constantly pressed to make hard decisions about whom to keep tabs on, and when to cease surveillance.
Ray Boisvert, a former assistant director of intelligence, said he could not comment on specific cases, but his work involved hard choices. "I sucked my breath back many times, to go 'Okay. Drop them. Move to these people,' " he said.
In London, a local mosque held a news conference Tuesday saying that the two men were unknown to members of the prayer centre. RCMP and CSIS officials visited the same mosque last month to encourage young Muslims to report extremism to authorities.
A previous generation saw an influx of Greek residents to the city. Mr. Katsiroubas grew up in an Orthodox Christian faith, but converted to Islam in his teens. He changed his name to "Mustafa" in Grade 9, according to the London Free Press.
At Perfect Bakery Pastry Shop in London, the shop's owner said Mr. Katsiroubas's father has been a loyal customer at the bakery for 30 years, coming to buy Greek olive oil and pastries.
"It's a good family, a very good family," said Tom Tserotas. "I feel sorry for the father because the father is a very good man."
With reports from Nicholas Boisvert and Katrina Clarke in London, Ont., Josh Wingrove in Edmonton, Ian Bailey in Vancouver and Campbell Clark in Abu Dhabi