These two saints were greatly honored and prayed to by the early Christians. The feast of these two martyrs was included in the Roman calendar of saints by Pope Vigilius in 555.
Marcellinus was a priest and Peter assisted Marcellinus in his ministry. Both very bravely practiced their Christian faith. They served the Christian community fearlessly and with great self-sacrifice even though they knew that their lives were in danger.
When Emperor Diocletian began punishing Christians for their faith, many Christians were killed. St. Marcellinus and Peter were also killed along with many others. They were beheaded.
But before they died, they were forced to dig their own graves. They were taken to a hidden spot, deep in the Silva Nigra forest, to do this difficult job.
Years later, their graves were discovered in that remote spot. Their executioner, the man who cut off their heads, asked for God's forgiveness and repented of the killings becoming a Christian himself.
He led devoted Christians to the remains, which were then buried in the catacomb of St. Tiberius. Pope Gregory IV sent the relics (or remains) to Frankfurt, Germany, in 827. He believed that the relics of these two saints would bring blessings to the Church in that nation.