University of Chicago students Nathan Leopold Jr. and Richard Loeb (both pictured) murdered a 14-year-old boy in a thrill killing out of a desire to commit a "perfect crime".

The University of Chicago is a private research university in Chicago, Illinois, United States. Its main campus is in the Hyde Park neighborhood.

Nathan Freudenthal Leopold Jr. and Richard Albert Loeb, usually referred to collectively as Leopold and Loeb, were two American lovers who kidnapped and murdered 14-year-old Bobby Franks in Chicago, Illinois, United States, on May 21, 1924. Leopold and Loeb, both students at the University of Chicago, were respectively aged 19 and 18; they committed the murder – characterized at the time as "the crime of the century" – hoping to demonstrate superior intellect, which they believed enabled and entitled them to carry out a "perfect crime" without consequences.

A thrill killing is premeditated or random murder that is motivated by the sheer excitement of the act. While there have been attempts to categorize multiple murders, such as identifying "thrill killing" as a type of "hedonistic mass killing", actual details of events frequently overlap category definitions making attempts at such distinctions problematic.

A perfect crime is a crime that is undetected, unattributed to an identifiable perpetrator, or otherwise unsolved or unsolvable. The term is used colloquially in law and fiction for both crimes committed as crimes foremost, and those committed as a kind of technical achievement on the part of the perpetrator.