Arcan Cetin’s actions and social media could lead you to multiple rationales – mentally snapped, upset at former girlfriend who used to work at the place of the shooting.
Here’s another. His Tumbler page had a chant to Allah and a picture of Ted Bundy on it.
He has contact with someone ‘@meowfraulein’ who has his picture as an avatar and the following pictures. Sounds like police might want to talk to this person, who appears to be female by the description ‘fraulein’.
These are shared with Cetin.