Early in the xyth century, a Roman nobleman commissioned three famed artists of the day to paint their versions of Ecce Homo (Pilate presenting Christ to the mob). He bought the one that pleased him best, by Lodovico Cigoli, and eventually it passed to the Pitti Palace at Florence. Another version, by Domenico Passignano, is lost. The third, by the great Michelangelo Merisi da Caravaggio, also disappeared.
In the centuries that followed, the fate of Caravaggio's painting has often tantalized art historians. It was not until Genoa's directress of fine arts began to get curious about a neglected painting which had long...