The "Monster of the Andes," Pedro López was convicted of killing 110 girls, but some criminologists believe he may have killed as many as 300. López traveled between Columbia, Peru, and Ecuador throughout the 1970s, picking up and murdering his victims. López claims that, at his peak, he was killing up to three people a week. But the most disturbing part of this story is the aftermath. In 1998, López was released from his psychiatric unit for "good behavior." His whereabouts are currently unknown.