Of course, because what else could he be but mentally ill?

“‘We can’t confirm or deny (the reports), we are checking whether there may be an Islamist background,’ a police spokesman told AFP.”

Here you go, Berlin police: yes, there is. Don’t thank me. This one is on the house.

“Police probe Berlin U-Bahn knife attacker for Islamist motive,” AFP, January 2, 2018 (thanks to the Geller Report):