It sounds like it could have been a case of obsession/stalking. There are some real strange people out there, and unfortunately, they often fixate on young women.
I’ve been stalked, and received sexually explicit letters without return addresses in the mail. I never knew who the stalker was. I knew another person who was stalked, and her stalker was arrested loitering with a gun in the parking lot where she worked.
I wonder if the killer posted to her twitter or facebook account?
What I read was that he didn’t even know who she was, that he had travelled to the area to kill someone, anyone.