A painted panel representing 'Saint Gregory the Great and Saint Stephen Protomartyr', appearing on the antique market and attributable to Pietro Grammorseo, proves to be the twin of the 'Saint John the Baptist and Saint Lawrence Protomartyr' in the Musée des Beaux-Arts of Besançon, already attributed to the Flemish artist. These two works, together with a third panel representing the half-length figures of 'Saint Thomas the Apostle and Saint Roch', allow us to begin the reconstruction of a polyptych executed by Grammorseo in the Piedmontese area between Vercelli, Casale Monferrato, Alessandria and Asti during the 1520s. It was at this time, in the area where Gandolfino da Roreto and the brothers Giovanni Martino and Francesco Spanzotti were active, that his unique style became established, characterized by sharp naturalistic details, touches of eccentricity and a mystical imagination dear to painters like Albrecht Dürer, Hans Baldung Grien and Mathis Grünewald.