I’m going to guess Grad Student.
I saw a photo of him lying on the ground after they captured him…a skinny white guy wearing those navy blue warm-up pants with a white side stripe, no shirt, but he appeared to have something black over his head (a hood?). I
Incidentally, not sure if it’s connected, but they caught a guy in Boulder, CO today who apparently was planning on blowing up a building at UCLA (in CA). Very strange, no information on that guy.
Grad students have done this kind of stuff once or twice before, so that’s a good guess.