The sacristy was commissioned by the Magnificent Pandolfo Petrucci, Lord of the City of Siena from 1487 to 1512, as his funerary mausoleum. The austere wooden choir carved by Antonio Barili in 1497 borders the walls while the extraordinary sculptural group in polychrome terracotta representing the Lamentation Over the Dead Christ, made by Giacomo Cozzarelli at the end of the fifteenth century, is housed in the niche behind the altar. Around the lifeless body of Christ we have the Blessed Virgin and the mourners (Saint John the Evangelist, Joseph of Arimathea, Nicodemus, a Mary and Mary Magdalene), whose faces reveal a sorrowful and dignified involvement. Most probably, there was also a statue of Saint Bernardino among these figures, a copy of which is now in the friary’s Oratory. Cozzarelli also created Pandolfo Petrucci’s tombstone and a beautiful marble lavabo with the family crest.