Know the Evil

I am a criminal psychologist in the city bureau, and the recent three dismemberment cases have shocked the city. The scene was eerily clean, and the victim himself was the only one in the surveillance camera. I repeatedly simulated the murderer's psychology, but I always got stuck at a certain key point, as if someone had forcibly erased something. It wasn't until the fourth case happened that I found my own DNA in the victim's fingernails. "Found it." In the darkness, the man who looked exactly like me smiled at me. "Now, it's your turn to guess which of us is the murderer."