Death Note
The best detective in the world, an eccentric genius named "L", works with the Japanese police, as well as Light's own father, to find out Kira's identity and catch him. He suspects all along that it's Light, who, as a part of the police department, works alongside L in the investigation. It becomes a contest of wit and intelligence between L and Light, both of whom are very clever. At one point, Light temporarily gives up the Death Note, along his memories of it, as an ally continue writing the names of criminals. This "proves" to the police that he is not Kira. However, he later gets the Death Note back and kills L with it.