According to federal authorities, 43-year-old Tommy Watson of Clayton and 34-year-old Johnnie Lee Nelson, of Bridgeton, are both facing charges.
Authorities say the men were involved in fighting, training, and transporting pit bull type dogs. The operation ran from August 2017 through March 2019.
Watson and Nelson are accused of posting videos of live dog fights, training dogs for fights and the killing of dogs who did not perform well.
Nelson was arrested last week and Watson surrendered to authorities on Monday.