Peter Savino got a better deal than Gravano in order to rat on Gigante, who had been good with him. Gravano did mob killings, Savino was killing non mafia members who he dealt drugs with, unknown to Gigante. I think he killed them after meeting for fake deals, then would kill them and take the drugs or the money. Outside of his working with Genovese on the windows skim, there is little out there about him. Even the news stories on his murders are tough to find. If not for Savino, and Gigante getting fooled into trusting him, Gigante may have had a chance to win his RICO case.