According to certain very unreliable "Acts", Boniface was a Roman citizen who for a time lived in sinful union with a noble woman named Aglae. Upon his conversion he determined to do penance by seeking the remains of martyrs and giving them honorable burial. At Tarsus he found many confessors about to be martyred for professing the faith; he kissed their chains and encouraged them to bear their sufferings courageously, assuring them that everlasting rest would follow a brief struggle. Finally he himself was taken captive, his body mangled with iron hooks, and boiling lead poured into his mouth. In spite of excruciating pain only one cry came from the lips of Boniface: "I thank You, Christ Jesus, Son of God!"

When Aglae, who in the meantime had likewise repented and was devoting herself to acts of virtue, was informed by an angel of the martyr's death, she hastened to inter the sacred remains in a church erected to his honor. His martyrdom took place on May 14 in Tarsus, a city in Cilicia, during the reign of the Emperors Diocletian and Maximian.

As a penance for his sins, Boniface sought out the remains of martyrs and provided honorable burial. Such an act of penance today would appear strange, even though motivated by love and contrition. And yet it was an act wholly pleasing to the Lord. This penitent became a martyr himself, and suffered the most excruciating torments during which he continuously repeated: "I thank You, Christ Jesus, Son of God!"

http://www.catholicculture.org/culture/liturgicalyear/calendar/day.cfm?date=2014-05-14