“He’s the Pope. He’s the Ex-Pope. They’re private detectives.”
Benny: “It will take a miracle to solve this case!”
Francis: “Good thing they called us in!”
“Pope and Pope, Thursdays at 8, on Fox!”
Alternately, Benedict XVI was secretly studying forensic pathology in his spare time, and resigned to follow his true calling, in which case it gets named CSI: Vatican City.
I could have gone with the “Popes by day, superheros by night!” angle, but you don’t want to strain plausibility.