Caesar Bonventre was killed because he and Baldo Amato were shaking down drug dealers and one of them happened to be Anthony Aiello, who was with Rastelli. Rastelli then called Bonventre and Giovanni Ligammari to a meeting over it. Bonventre denied that he had taken kilograms of heroin from Aiello and stormed out, with the disrespect of walking out on the boss ultimately being what got him killed. Massino testified that Rastelli wanted to kill Amato as well but he got a pass because he was just doing what his captain (Bonventre) told him