The records state that Pietro was born at Sant’Angelo Limosano, near Isernia, in 1215. His parents were Angelerio and Maria. In 1231 he became a Benedictine monk at the monastery of S.Maria in Faifoli, where he remained until December 1234, when he set off for Rome to seek permission from the pope to become a hermit. Pietro crossed the Mainarde massif and spent some time in a grotto above Castel di Sangro. Subsequently he went to Palena, to the Madonna dell’Altare refuge, where he spent three years in penitence, and in 1238 he resumed his journey for Rome where he received the holy orders, leaving the city in 1241.
On his return he decided to retire to Mount Morrone. In June 1246 Brother Pietro decided to move to an even remoter and more inaccessible retreat. He penetrated the Maiella valley and sought refuge amongst the same woods two hundred years earlier Desiderio, prince of Benevento, had lived in solitude before becoming Pope Victor III in 1080. There he stayed for over forty years, during which time he built the monastery of Santo Spirito and expanded both San Bartolomeo in Legio and San Giovanni in Orfento.
In 1293 Brother Pietro withdrew to S. Onofrio al Morrone. On July 17 1294, he was informed that he had been elected head of the Catholic Church, he was 79 years old.
The same evening he descended to the abbey where the King of Naples awaited him and here he remained until July 24 when he set off for L’Aquila.
Here was crowned pope on August 29, with the name of Celestino V. He reached Naples on November 5, took residence at Castel Nuovo, and here led an existence that resembled that of a hermit rather then that of a pope. Despite opposition, however, on December 13, Clestino V entered the consistory renounced his role as pope and once again put on his hermit’s tunic. On December 24 Cardinal Gaetani was elected with the name of Bonifacio VIII.
In the meantime, with the help of some of his monks, Pietro returned to Morrone, but he was forced to hide and then flee. Bonifacio VIII’s emissaries seized him and took him to Anagni. In August 1295 the Pope confined him to the fortress of Fumone where the old Hermit died on May 19, 1296.