범죄 다큐멘터리 유튜브 썸네일

A dark, mysterious YouTube thumbnail for a true crime documentary. A moody black-and-white photograph of [an open handwritten letter] lying on a cluttered detective's desk, dramatically illuminated by a single warm desk lamp casting deep shadows. A large, distressed red question mark is stamped across the center of the image. Documentary title text reads "[UNSOLVED]" in a classic typewriter font. No human faces visible, cinematic film noir atmosphere, high contrast.