Nathan Freudenthal Leopold Jr. (November 19, 1904 – August 29, 1971) and Richard Albert Loeb (June 11, 1905 – January 28, 1936), usually referred to collectively as Leopold and Loeb, were two American murderers who kidnapped and killed 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 and were engaged in a relationship at the time of their crime. 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.
Leopold's and Loeb's families retained Clarence Darrow as lead counsel for their defense.