As i mentioned,I don't want to give out any spoilers,but it's true that the actual gunman isn't seen.
I'm referring to the back story and the actual person who gave the order.
I agree that going by just watching the series,that it was Haydu,but that's assuming Tony was given correct info.
He might not even be aware of the actual details of Dickie's death.
i feel that the movie threw a little curve at us as far as who gave the order,but that is only my opinion,and nothing more.