Independent sources in Canadian security and government tell The Canadian Press that Mujahid Enderi, who goes by the anglicized name "Ryan," a Libyan-Canadian from southwestern Ontario, is under investigation and being sought by police.
All of the sources requested anonymity because they were not authorized to speak publicly about the hunt for Enderi.
Enderi, from a devout Muslim family in London, Ont., dropped off the radar last year and is believed to have travelled overseas around the same time as three other young men from the same community, two of whom died in the siege at Tiguentourine Gas Plant, 1,600 kilometres southeast of Algiers.
Enderi attended the same high school as Ali Medlej, Xristos Katsiroubas and Aaron Yoon, but was several grades behind them.
The Jan. 16 attack and four-day siege on a gas facility ended with the deaths of 37 hostages and 29 terrorists. Medlej and Katsiroubas took part in and were killed in the deadly attack. Their bodies were identified by RCMP forensic specialists.
RCMP Commissioner Bob Paulson would say little Friday about a fourth Canadian involved in the investigation into how Medlej and Katsiroubas joined the attack organized by an African offshoot of al-Qaida.
"We're continuing to focus our investigation on anybody who may have contributed to their presence there," Paulson said in Calgary.
"In that sense we still have an open book on what happened there."
Government and security sources in Ottawa said they're concerned that Enderi remains at large. Paulson said his investigation into the Canadian connection involves Mounties at home and around the world.
He also warned Canadians to be aware of the dangers this case highlights.
"It is a little frustrating because I don't think people fully understand the phenomenon of home-grown radicalization," he said.
"It's something I think we need to get serious about. We need to co-ordinate our efforts in our communities and make sure we're able to prevent these things."
Yoon, who didn't go to Algeria, was arrested and is being detained in Mauritania. Authorities there say Yoon was recruited to train at an al-Qaida camp in northern Mali and had ties with al-Qaida in the Islamic Maghreb, or AQIM. Yoon denied any terror connection in an interview with the CBC.
Enderi's whereabouts remain a mystery to federal authorities. His association with the other young, radicalized men is equally murky, but security officials insisted there is a connection which agents are probing.
Enderi's younger brother answered the door last week at the family residence in London and said he wasn't there.
Ubada Enderi said he didn't want to talk about his brother because he was worried about his words being taken "out of context."
He did say that the young man was "definitely not" involved in the Algeria attack. "I know for a fact," Ubada said, but wouldn't elaborate.
Fellow students, neighbours and others who know the family in London were tracked down over the last few days, and shed some light on Enderi — but few wanted to speak publicly.
Someone who knows the family but asked to remain anonymous said the elder son "went overseas" some time last year.
Another neighbour, John Krogman, said when the father, Abdul, was at home, the Enderi children — two boys and a girl — were behaved but when he was not, the kids would run free in the neighbourhood.
Krogman said the mother wears a burka and doesn't talk much to the neighbours. He said he hasn't seen the oldest son around the family home for a while, perhaps two years.
"He was always respectful to me," Krogman said, but was "kind of mouthy" at times to others and got into disputes with some of the other people on the street.
There is no animosity toward the family in the neighbourhood, Krogman said.
"We genuinely care about the family and how they're doing," he said.
Ahmid el Turk, one of the directors of the London Muslim Youth Association remembers Enderi coming in sometimes, but not since about 2010.
He said the talk in the community is that Enderi went to Libya.
Katsiroubas and Enderi became friends and spent time together around 2007, after Katsiroubas appears to have dropped out of school.
Enderi went to London South for two years, then attended Saunders Secondary School for Grade 11, finishing in 2010. It's unknown where he went after that and he is not believed to have completed Grade 12.
The RCMP took the unusual step last week of confirming that Medlej and Katsiroubas died in the attack, but would not discuss who else they have under investigation.
They instead appealed to the public to help them determine when the two men left the country and who else might be involved.
"Who individuals might hang out with, who may or not have a good or bad influence on someone that may lead to certain behaviour, or observing these people and how they behaved and clues that people may have had either in discussions or in just in social settings with these people that may have triggered: 'Oh that's odd,'" RCMP Supt. Marc Richer said last week.
"It may be many things, but if people around these two individuals noticed something that didn't fit over the course of time before these events that they believe might be useful, that's what we're looking for."
The Mounties may be able to get some of that information from Yoon, 24, who told the CBC last week that he went to North Africa to study the Qur’an.
Mauritanian authorities said Yoon had ties to al-Qaida's affiliate in Africa.
"This Canadian citizen stated to investigators that he had come from Morocco to study the Qur’an and Islamic law before being indoctrinated by salafist jihadists who recruited him to join AQIM in the north of Mali," a Mauritanian judicial official, who spoke on condition of anonymity, told the Associated Press.
Yoon told the CBC that he had no involvement in terrorist activities.
He was convicted last July for having ties to a terrorist group and posing a danger to national security, the Mauritanian official said.
The Canadian government has said its officials continue to provide assistance to Yoon as they would for any Canadian detained abroad.
"This assistance should not be construed as a belief of his guilt or innocence," a spokesman for Diane Ablonczy, minister of state of foreign affairs, has said.
Yoon told the CBC in a telephone interview from prison that he had been tortured and beaten behind bars. He also said he didn't know how the two Canadians killed in Algeria earlier this year had become linked with militants.
— With files from Bill Graveland in Calgary
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