On the evening of May 28, 1606, the long-smouldering animosity between Ranuccio Tomassoni and Caravaggio flared up into a formal duel, which took place on the tennis court of the French ambassador to Rome. Caravaggio pierced his opponent’s femoral artery (thigh) with his dueling sword, causing him to bleed to death in a very short time.
The nature of the injury, close to Tomassoni’s groin, may suggest that Caravaggio intended to wound his opponent sexually. Wounds were meaningful in the honour culture of the time, so, for example, a facial wound might be inflicted to avenge an insult to reputation, or loss of face, while a genital wounding or attempted castration might mark a dispute over a woman.
Caravaggio and Tomassoni may still have been competing over Fillide Melandroni, or perhaps they had argued over Tomassoni’s wife—the presence of Tomassoni’s two brothers-in-law as seconds gives some credence to the latter hypothesis.
Whatever the cause, the killing would have a profound effect on the rest of Caravaggio’s life. He fled Rome in its immediate aftermath. Duels themselves were against the law, and thus committing murder during a duel was a grievous offense.
He was convicted in absentia of murder and made subject to a bando capitale, a capital sentence, which meant that anyone in the Papal States had the right to kill him with impunity in exchange for a reward. If they were unable to produce his body, his severed head would suffice. Caravaggio's paintings began, obsessively, to depict severed heads, often his own, at this time.
Ranuccio Tomassoni was a gangster from a wealthy family. The two had argued many times, often ending in blows. The circumstances are unclear, whether a brawl or a duel with swords at Campo Marzio, but the killing may have been unintentional.
Many rumours circulated at the time as to the cause of the fight. One possible reason being a quarrel over a gambling debt and a pallacorda game, a sort of tennis, and this explanation has become established in the popular imagination. Other rumours, however, claimed that the duel stemmed from jealousy over Fillide Melandroni, a well-known Roman prostitute who had modeled for him in several important paintings; Tomassoni was her pimp. According to such rumours, Caravaggio castrated Tomassoni with his sword before deliberately killing him, with other versions claiming that Tomassoni's death had been caused accidentally during the castration. The duel may have had a political dimension, as Tomassoni's family was notoriously pro-Spanish, whereas Caravaggio was a client of the French ambassador.
Vatican documents released in 2002 support the theory that the wealthy Tomassoni family had him hunted down and killed as a vendetta for Caravaggio's murder of gangster Ranuccio Tomassoni, in a botched attempt at castration after a duel over the affections of model Fillide Melandroni.