Thanks folks for the input. One of the things I wondered about was since the Corleones (Michael) got snagged by the Feds-how we are never told, other than Pentangeli-could those sources have also implicated Hagen. Tom was privvy to a lot of information and somewhere along the line someone other than Pentangeli may have stepped forward OR some other hard evidence; i.e. photos, notes, witnesses. I tend to think that Michael's arrogance (and "underestimation" [Turnbull])might have led him to use Tom and therein the potential for disaster if the trial every came to fruition.