Thomas Campbell is a drug kingpin in Chicago running the distribution of isotonitazene. When Dell Cotner was busted for being in possession of his merchandise, courtesy of Kelly Severide, he ordered his men to rough up Severide. After Kelly killed one of his men, he and Cotner tracked down Severide and his newly-made wife, Kidd, to Benny's cabin and tried to kill him. He and Cotner were arrested that night by Detective Pryma. Apparently, he had a mole within the Chicago Police Department by the name of Danny Kavanaugh, who was also stripped of his rank and arrested.