" What further does it tell us? This: that the assassin was left-handed. How do I know this? I should not be able to explain to you, gentlemen, how I know it, the signs being so subtle that only long experience and deep study can enable one to detect them. But the signs are here, and they are reinforced by a fact which you must have often noticed in the great detective narratives—that all assassins are left-handed." "By "

― Mark Twain , The Double-Barrelled Detective