There are many
forged passports being used by refugees fleeing the Middle East (and elsewhere) towards Europe,
reportedly being fabricated in Turkey. Additionally, how many copies of the same passport are being used? How many of those passports are sold on after arrival in Europe (by those desperate for any source of funds)?
Indeed, it has been
suggested by some security sources that the passport found at one of the scenes is fake.
I don't see any clear proof published thus far by any reputable source linking any of the perpetrators to the most recent refugee migration from the Middle East/Africa in to Europe. It's far too early in the investigation to deduce such (other than in the blinkered minds of small minded commentators for whom jumping to conclusions that serve their own prejudices and agenda is a way of life).