Serial killings committed by psychopaths who somehow manage to avoid being caught and convicted of their crimes. The Zodiac Killer, who terrified the San Francisco Bay Area in the late 1960s and early 1970s with a string of murders accompanied by bizarre cryptograms and letters to the press. The Zodiac is not alone, however. The following rogues gallery presented in no particular order, since they are all equally hideous lists some of the ones who got away with the worst crimes imaginable.