Kenney said the Lebanese Canadian man arrived in Canada from Lebanon at age eight and lived in Vancouver with his mother before becoming a citizen, then returned to Lebanon when he was 12.
Bulgarian authorities say that's where they believe the man is now, along with the other suspect in the July attack, which killed five Israeli tourists, a Bulgarian bus driver and a third suspect — the bomber himself.
The names of the suspects are known, the suspects are based in the same country and "we have asked Lebanese authorities to assist in our investigation," Stanimir Florov, head of Bulgaria's anti-terror unit, said Wednesday.
He did not elaborate.
The three are believed linked to Hezbollah, the Shiite militant group and political party that Canada and the U.S. both have designated a terrorist organization. Hezbollah has denied any involvement in the attack.
A spokesman for Foreign Affairs Minister John Baird said the government is continuing to work with Bulgarian officials to obtain more information.
The Lebanese-Canadian individual wasn't in Canada very long, Kenney said, although he may have returned to Canadian soil on more than one occasion since leaving as a boy.
"I understand he returned to Lebanon, I understand he may have been back a few times since then but has not been a habitual resident in Canada since the age of 12," Kenney said.
Bulgarian authorities have said the activities of both suspects could be traced to their home countries. The other man reportedly holds an Australian passport.
While the Lebanese-Canadian individual may not have lived in Canada recently, Kenney said the controversy raises the question of what to do about citizens who go abroad to commit acts of terror.
"Canadian citizenship is predicated on loyalty to this country, and I cannot think of a more obvious act of renouncing one's sense of loyalty than going and committing acts of terror," he said.
He suggested the government ought to look at what other countries do and consider a mechanism for stripping Canadian citizenship from those involved in terrorist acts abroad.
Conservative MP Devinder Shory currently has a private member's bill before the Commons that, among other things, would revoke citizenship from dual nationals if they engage in an act of war against the Canadian military.
Permanent residents who commit such an act and who have applied for Canadian citizenship would see their application being deemed as withdrawn.
Perhaps the bill could go further, Kenney mused.
"I think that perhaps we should consider working with Mr. Shory to broaden the scope of his bill to include not just acts of war committed against Canada by Canadian citizens as grounds for deemed renunciation or revocation of citizenship," he said.
"Perhaps we should also consider acts of terrorism as grounds for deemed renunciation if committed by dual citizens who carry Canadian nationality."
The last time Canada found itself in a debate about the merits of dual citizenship, Lebanese-Canadians were again at its centre.
In 2006, the Canadian government evacuated 14,370 Canadians from Lebanon after the escalation of conflict between that country and Israel. How many were dual citizens was unclear. The cost of the evacuation effort was estimated at $94 million.
The price tag and reports that many dual citizens later returned home led to questions about what responsibility the government actually had to people who held Canadian passports but hadn't paid taxes or lived in Canada for years.
Kenney said the conclusion at the time was that most Canadians supported the idea of dual citizenship.
"Generally Canadians are really intolerant of those who would seek to abuse the country's generosity, so this tells me that they believe the vast majority of the country's dual citizens are bona fide — and I agree," he said.
"I think where we might want to make a distinction is amongst those dual citizens who have completely rejected any sense of loyalty to Canada (and) gone out and committed terrorist crimes."
The New Democrats, meanwhile, cautioned restraint.
The Conservatives tend to rush for legislative solutions to problems they haven't fully explored, said Opposition Leader Tom Mulcair.
"Nobody is ever going to argue that somebody who has done something that awful is going to maintain their Canadian citizenship if they've been abusing it anyway,"
"Let's take the time to find out what he's actually putting on the table, because I'm used to Mr. Kenney's interventions, which tend to be very punctual, based on one single event, and there's no follow through on it."
Interim Liberal leader Bob Rae said if the government wants to do a full review of the issue of dual citizenship, that would be OK, but a policy shouldn't be made on the fly.
"Do we want to have two or three different kinds of citizens? Do people who perform criminal acts, who are guilty of criminal acts, are they routinely deprived of their citizenship? No," Rae said.
"So is it more complicated? What are the consequences of doing that? Is it constitutional? These are things the minister of the Crown should be thinking about before he comes to a scrum and announces some kind of, frankly, knee-jerk response."
— with files from The Associated Press
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