People have a short memory  but it was the Conservatives who banned the niqab. During the last election they waged a culture war on Muslims. It was Harper and his party who availed themselves of every opportunity to tie Muslims to terrorism.  It was the Harper government who tied Muslims to "barbaric cultural practices" and created a snitch line . Ms. Leitch who is running for leadership of the party  is still at it and has endorsed many of Trump's positions  regarding Muslims .

In short the full weight of government the Conservatives were consumed with spreading fear against Muslims . While they may not be directly responsible for the murders their words and actions gave license to them. 
Check out http://www.macleans.ca/politics/how-kellie-leitch-touched-off-a-culture-war/