You don't know that for a fact. It's plausible it could be a terrorist and it's also plausible it may be another wacko serial killer.
It's plausible, and I do believe the ties should be looked into. I just don't consider it very likely, and some of the rhetoric coming from earlier in this thread - that we should kick all the Muslims out, etc, seems a little excessive given that there's zero subsantiated evidence pointing toward terrorism.