On one of the tv documentaries Leonetti said Scarfo told him if the philly guys didn't follow his orders he was going to bring down guys from NY to kill all of them and start over from scratch.

The Vic and Gas show got pretty psychotic too. They were killing everyone and of course Casso gave the infamous order to "Whack New Jersey" meaning the entire NJ faction of the Lucchese's.

But IMO no american gangster killed like Toto Riina did in sicily. He killed everyone, women, children, cops, judges...everyone. I think he makes guys like Scarfo and Casso look pretty tame. "The Beast" killed like nobody else i can think of.