The story is related in the legend of St. Sebastian that Chromatius, prefect of Rome, condemned several Christians to death. The prefect, however, was converted by St. Tranquillinus and baptized by Polycarp. Tiburtius, the only son of Chromatius, was also baptized through the persuasion of St. Sebastian, who was his godfather in baptism. Tiburtius during the persecution of Diocletian lay hidden in his father's house. Accused by a traitor, he was brought before the prefect Fabianus and tried. He confessed his faith which he confirmed by a miracle, for protecting himself only by the sign of the cross he walked over red-hot coals barefoot without suffering any injury. But the miracle was ascribed to magic and Tiburtius was beheaded at the third mile-stone of the Via Lavicana. This was in the year 286. The spot of execution was called, "at the two laurel trees".
Saint Susanna, virgin and martyr, is said to have been the daughter of St. Gabinius. She was beheaded about the year 295, at the command of Diocletian, in her father's house. This house and the adjoining one belonging to her uncle, the prefect Caius, which were near the two laurel trees, were turned into a church, later the titular church of St. Susanna ad duas domos (cf. Kehr, "Italia pontificia", I, 61 sq.). The authenticity of the Acts of Sts. Sebastian and Susanna has been rightly questioned; however, the martyrdoms and the day of death (11 August) are established by the witness of the oldest Martyrologies and the earliest places of worship.
