I have just been listening to a BBC podcast (The Report 28th November 2013) about corruption in the Vatican and the resignation of Pope Benedict. The programme's thesis was that Benedict resigned because he was unable to control the level of corruption by Vatican officials.
There was a bit about padding of contracts and other shenanigans.
The really interesting bit was about the Institute for the Works of Religion (aka the Vatican Bank). This was set up to allow the church to transfer money about the world for the purpose of doing good works.
However, it also has 30,000 private accounts. That's right, there are allegedly 30,000 people who have their own personal accounts with the Vatican Bank and because of the banks legal situation these accounts are totally immune from outside scrutiny. Even if used for tax evasion, money laundering and bribes.
Having such an account would be every crooks dream and being able to provide such accounts would confer enormous power.
Forget the Da Vinci Code. The real secret worth killing for would be a list of those account holders.