VATICAN CITY –  The Vatican publicly unveiled a handful of bone fragments purportedly belonging to St. Peter on Sunday, reviving the scientific debate and tantalizing mystery over whether the relics found in a shoe box truly belong to the first pope.

The nine pieces of bone sat nestled like rings in a jewel box inside a bronze display case on the side of the altar during a Mass commemorating the end of the Vatican's yearlong celebration of the Christian faith. It was the first time they had ever been exhibited in public.

Pope Francis prayed before the fragments at the start of Sunday's service and then clutched the case in his arms for several minutes after his homily....