He is the patron of inquisitors.
Symbol: Dominican with a large knife in or splitting his head; holding a knife; man with a knife in his head and a sword in his breast.
Things to Do:
•As he lay dying, it is said, Peter wrote the word Credo on the ground with his own blood. To us also may the Creed be a source of blessing in life and in death! To that end we might occasionally meditate on one or another of its articles. Devoutly, reverently the words should pass our lips, especially at Mass. Remember that martyrs' blood has flowed for all its phrases.
http://www.catholicculture.org/culture/liturgicalyear/calendar/day.cfm?date=2014-04-29