Who is Mike Scully, and what is Sinclair muckraking through the description of this character's actions?

Mike Scully is the most powerful man in Packingtown. Scully owns the trash dumps and the lake of fetid water that is used for ice in the winter. There have been numerous scandals associated with Scully, but he always pays someone else to take the blame and then that person leaves the country. Scully is the leader of the “War-Whoop League,” a political club. This club also holds entertainment events, such as cockfights and dogfights, for the workers. Scully’s “Indians,” as they are called, are responsible for rounding up the immigrant men and making them citizens so that they can vote. Scully is so powerful that “even the packers [are] in awe of him.”