 According to the "Passion of St. Sebastian", the four saints were soldiers who refused to sacrifice to Aesculapius, and therefore were killed by order of Emperor Diocletian (284-305).The bodies of the martyrs were buried in the cemetery of Santi Marcellino e Pietro, on the fourth mile of via Labicana, by Pope Miltiades and St Sebastian (whose skull is preserved in the church).Miltiades decided that the martyrs should be venerated with the names of Claudius, Nicostratus, Simpronianus and Castorius; these names — together to a fifth, Simplicius — were those of five Pannonian martyr stonemasons.