Anastasia defended himself in front of the Commission by saying Mangano actually was gunning for him. Nobody knows, I suppose, if Anastasia spoke the truth that time but it was a well known fact that the two of them did not stand eachother. They actually engaged in a scuffle with eachother, in front of other mafiosi (during a meeting) which Mangano lost because of his smaller frame. Just prior to his murder, Mangano expressed his worries about younger guys in his Family forming an alliance to take over the Family. Many of them were under Anastasia´s control. So Mangano could not demote or kill Anastasia without risking a full fledged war.

The main suspect in the Mangano killing, Jack Sparacino (an alleged Mangano member), was brought in for questioning by the police. But he was released when they, at least officially, couldn´t find stronger evidence against him to hold or charge him. I say officially because Sparacino was later found murdered and it was said that he had given up some info to the police on the murder.