Peter’s father was a city councilor, his mother was from a noble family, and the boy was raised in a pious household. He received a good education, and was drawn early to religious life, with a personal devotion to Our Lady of the Rosary. He joined the Dominicans in Piedmont, Italy at age 16. He continued his studies, and was ordained at age 25, and was a noted preacher throughout northern Italy. He worked to bring the heretical Waldensians back to the Church, and was appointed inquisitor-general of the Piedmont.

In January 1365 Peter and two Dominican brothers went on a preaching mission through the mountains between Italy and Switzerland, working from the Franciscan friary at Susa, Italy. Peter’s preaching brought many back to the faith, which earned him the anger of the Waldensians. Three of the heretics came to the friary, asked to see Peter, and then murdered him at the gate.