As I've posted many times: Why would Tony Rosato utter that line to a guy who was only seconds away from death—unless he intended him to live? Doesn’t it prove that Roth had planned for the New York cop to come in and foil the “murder attempt,” so that Frankie would live to indict Michael?

it’s also possible that Coppola, the most careful of directors, allowed it to remain because it fit the plot, even though the Rosatos intended to kill Frankie all along. “Michael Corleone says hello” was intended not for Frankie—but for Richie, the bartender, whose ginmill was being used to set up Frankie.
It’s obvious that Richie is a “civilian,” not a Made Man, and he’s nervous as hell about his bar being used for a murder (“Carmine, NO, not HERE!” he screams at Tony’s brother (played by Carmine Caridi) after the cop enters and Carmine draws his gun). The Rosatos know that Richie might be squeezed by the cops investigating Frankie’s murder. Richie would be too fearful of the Rosatos to identify them as the killers. Still, as a civilian, Richie is not bound by the code of omerta. So they hand Richie something he can give the cops so that Richie can get off the hook: “The murderers said, ‘Michael Corleone says hello.’ ” That line would set the police after Michael, and would be picked up by the press-- another nail into the coffin of Michael Corleone’s “legitimacy.” Clever Roth! [/QB][/QUOTE]

Once again, this proves one thing and one thing only....Turnbull is a good man.