This idea did not come from me, but it is worth posting and makes a case I do not recall having been made before on this oft discussed topic.

To get to the conclusion we need to ask some questions:

1. Who was smart enough to be counted on by Roth's people to do it?

2. Who would have had unfettered access to Michael's bedroom, and even if caught there by a servant or even Kay could explain?


3. Who was constantly being put down and rejected by Michael?

4. Who understood that the olive oil business was being supplanted by legitimate casinos in Vegas and Havana?

5. Who uderstood better than anyone that the business model of the Corleone family had changed from transactions based on Sicilian omerta and loyalty to a Jewish investor, foregin dictators and crooked Senators?
6. Who understood all the factors in point five beter than Michael?

7. After Michael's death who would replace him as unquestioned head of the family?

8. Who objected to the killing of Roth but not of Fredo?

9. Who could ( and did) get away with it because he was beyond suspicion?

10. Who saw Michael for what he really was?

The person who opened the drapes. Tom Hagen.