Missing Physical Evidence

I hid in the closet, and a man in a police uniform slowly walked into the room. Then, a pair of white-gloved hands holding a sharp knife stretched out directly from behind the man. The blood colored the white walls in the room. I didn't see the man's face, but I saw that the man was wearing a ring full of petals outside of his white gloves... This is the memory of my youth. As the captain of the Jia City Criminal Investigation Brigade, from the day I became a police officer, I have been pursuing the person who made me lose my childhood...