CSIS: 60 individuals with suspected terrorist links back in Canada
When asked why the 60 or so individuals who the agency suspects have returned to Canada after fighting overseas have not been charged, Coulombe said having information about threat-related activities does not necessarily mean that the charges can be laid in Canada.
"The threshold for us to launch an investigation, and the threshold to charge somebody under the Criminal Code, there's a fair bit of a difference here," he said. "Being able to prove that the person was actually in Iraq or Syria fighting or financing (terrorist groups)…is a difficult task."
Shaikh echoed Coulombe's statement, saying the only certain way to ascertain evidence would be to embed an undercover agent in ISIS, which create its own set of issues.
"But if you have someone undercover in ISIS, what kind of acts have they done to maintain their cover? Would that be somebody who can stand a cross-examination in court?" said Shaikh.
Shaikh said security forces in Canada are often left with two options for dealing with individuals who returned from overseas: monitor them for more intelligence and evidence of criminal wrongdoing; or encourage accepting an amnesty and getting involved in a "counter-messaging effort."
However, Coulombe stressed the importance of trying to prevent potential terrorists from leaving the country in the first place.
"I truly believe, as a country we have an obligation to prevent Canadians from leaving this country in order to conduct terrorist-related activities, and killing people overseas," he said