The painting depicts Saint Peter of Verona and, according to the records in the Book of Accounts, was commission by the friars of Santa Croce in Castel Bolognese between 1646 and 1647.  
Having entered the Dominican order of the Frati Predicatori in Bologna when he was barely fifteen, Saint Peter was assassinated with a blow of a large knife to the skull and the slash of a sword to the heart while he travelled from Como to Milan. Following a long-standing compositional layout in his repertoire, Guercino depicts him at the centre of a landscape in Dominican garments, kneeling at the instant of death, which he faced with great dignity. With the Gospel and the palm of martyrdom in one hand and the other resting on his chest, Saint Peter looks towards the two putti in the upper part of the canvas, perhaps added by Guercino at a later time in the hope of being forgiven for the delay in delivering the work.

One cherub is turned to the saint while the other directs our gaze to the background, where a small character is seen running away: this is probably Saint Peter’s assailant, Carino di Balsamo, who, according to legend, would in turn become a Dominican after repenting the murder had committed.