I have heard it was Carlo Gambino and the commission due to all the attention that was being brough by Columbo's Anti Italian Defamation League(I think this is the name of the group, if not then my bad)
The group Joe 'the Double Crosser' Colombo founded was the Italian-American Civil Rights League and since he was such a Chatty-Cathy around the media outlets I'm sure he worried the Commission. I heard he was asked on numerous occasions to stop and did not listen to the others.
