 Like many young Americans, including Frank Sturgis, David Ferrie and Harry Dean, Hemming joined an American effort to overthrow the Batista regime through the efforts of Fidel Castro.When Castro proved to be a Communist, and subjected some Americans to firing squads, most Americans "switched sides" and this included Gerry Patrick Hemming.who, in 1961, established Interpen as a means to attack and weaken the Castro regime.