Leopold and Loeb confessed to a heinous murder. Clarence Darrow argued for mercy.

Nathan Leopold had planned to visit Paris in the summer of 1924. Instead, he and Richard Loeb found themselves behind bars and on trial for the murder of Bobby Franks, their neighbor in Kenwood, an enclave of Chicago’s wealthy Jewish families.

He might have thought the murder would provide him with a little extra spending money in France. He and Loeb demanded a $10,000 ransom from Franks’ parents in a note signed: “Yours truly GEORGE JOHNSON”.

Instead, the typed letter provided another key piece of evidence for law enforcement...