The martyr-Pope St. Felix II governed the Church during the exile of Pope Liberius, in the middle of the Fourth Century. Simplicius and Faustinus were drowned in the Tiber, probably in 303, when the great persecution under Diocletian was at its height.
Beatrice, their sister, with the aid of the priest Priscus, recovered their bodies in order to give them burial; for which offence she was strangled in prison.
In the Fourth Century a basilica was built at the side of the sepulcher of the two brothers and their sister.
(Source: The New Roman Missal, Rev. F. X. Lasance)