Well, that explains a lot, thanks.

But what's about the Black Hand? Fanucci was part of it, right? They were blackmailers. It should have been in their interest to find out who dared to kill one of them, just in order to prevent that it will hapen again. They could have find out that it was Vito and take revenge but they didn't. Were they afraid of Vito? Unlikely, he wasn't a big shot at that time...