In the scene where Tom goes to the Brothel to "help" Senator Geary. Did the Corleones kill the girl themselves so that they could set up Geary and then save him from a career ending scandal, and a jail sentence for murder. Then they would have Geary right where they wanted him for the future help that they would most certainly need at some point.
Exactly. It was Michael's way of responding to the disrespect that Geary showed him in their initial meeting, getting Geary to get those Casino licenses for him, and basically his way of telling Geary that he would now be under his control.
But most of all, in my opinion, It was Michael's answer to :
"Because I intend to squeeze you. I don't like your kind of people. I don't like to see you come out to this clean country in your oily hair -- dressed up in those silk suits - and try to pass yourselves off as decent Americans. I'll do business with you, but the fact is, I despise your masquerade -- the dishonest way you pose yourself. Yourself, and your whole fucking family." It was a "Do you really know who you are f**king with, Senator?" response from Michael.
