London police say they’re considering laying terrorism charges against the man accused of killing members of a Muslim family out for a walk in in London, Ont. on Sunday because of their faith.

But getting the evidence needed to prosecute isn’t always easy under Canadian law.

“We’re talking here about the legal system. Not politics or not what you or I or anyone else might view as terrorism around the dinner table,” said University of Calgary law professor Michael Nesbitt.

“It’s a rather complicated area … because we don’t have a definition of terrorism in Canada.”

On Sunday, four people — Salman Afzaal, 46,