My dumb ass mixed up "missing" with "wanted" and thought Zen just reported a known cat killer to the police. I thought it was an asspull from the author to explain the deaths of the cats and wrap up the arc in one chapter. After reading the comments i realized it was yet another well executed...
My theory : The teacher is actually a good guy who was actually saving the cats all this time (like what most people here think). He'll die after the accident and become a "good" ghost similar to Miko's father. He willl be the first ghost that Miko interacts with and will help/be helped by her...