Baatz, Simon. For the Thrill of It: Leopold, Loeb, and the Murder that Shocked Chicago. HarperCollins, 2008 Amazon
I wish there were more case studies to examine in this field. It’s rare to find a documented sadomasochistic relationship in the pre-modern era; I shudder to think how easily the Munby-Cullwick papers could have been lost. Sometimes one must make do with what one can find. In this case, there’s the case of Nathan Leopold and Richard Loeb who probably would have been remembered as eccentrics if they hadn’t kidnapped and murdered a teenage boy, basically just to prove they could.
After their capture for the murder, the two men were thoroughly examined by physicians, neurologists and psychiatrists, who couldn’t agree on a diagnosis. Eventually they were found competent to stand trial. Their examinations and testimonies revealed both had vivid fantasy lives.