There are three pusher markers in the map but you can only interrogate two of them. We’ll go with Eugenio Calabrese since taking him out yields high rewards and deals high damage with the considerable amount of risk as well. He’s located in the cemetery. You can enter from the church’s side then circle around at the back so you can take out his guards stealthily. There’s one sentry so you can check his route then plan your ambush. Get to him to unravel another objective.
Buster Nunez owns a bar east of Bigmouth’s. You can sneak in at the back or go in the front door and shoot the guard first then shoot him to disable him. Take note that since there are customers, there will always be a chance that they’ll call the police after witnessing the violence. Work quickly, question Buster then leave the area immediately.