Gerald Posner is an investigative journalist and author of several books, including ones about the assassinations of JFK and Dr. Martin Luther King, Jr.

His latest book, God’s Bankers, is all about the Vatican’s finances, and how the Church got involved with the Mafia and money launderers.

We spoke with Gerald about how he followed the trail of the Church's money, what the Vatican Bank is used for, and the advice he has for investigative journalists.