Initially it was reported that he was “known to police”, a euphemism for “criminal”, and living in Germany illegally after arriving as a refugee.
This has been corrected now: He was “known to police” because he was a witness in a shoplifting while working as a store detective. And he is in Germany legally with a work visa.
Unfortunately, the false info spread like wildfire, and gives ammo to those on the right, even though nothing they demand of the government could have prevented this tragedy.