The poem is based on a real-life case. Under Roman law at the time, trials were not held in open court but rather by correspondence, whereupon each witness was required to submit a written statement for future adjudication. Browsing in a flea market in Florence in 1860, Browning came across a large volume of these written statements relating to the 1698 Franceschini case, and bought it on the spot. This volume – later known as the Yellow Book, after the colour of its aged covers – struck Browning as an excellent basis for a poem, but he was unable to get any further than the basic idea and often offered it as a subject to other writers, notably Alfred Tennyson, upon which to base a poem or novel. Luckily for posterity, there were no takers, and following his wife's death and his return to England, Browning revived his old plan for a long poem based on the Roman murder case almost eight years after the idea had first struck him.