I agree, Perisano is the rat. There may be others plus wire taps. The fact that they are actually naming Dom Grande speaks volumes in my view. Not to beat a dead horse but why would he use his own car in a hit and hold on to the weapon! That is just stunning to me. My best guess is a very simple one: he/ they panicked.
My guess was that Nicodemo was so furious at the disrespect Dipietro showed him at the card game (based on what I've read), that he saw red, consequences be damned.
