Since the rise of Adolf Hitler in Germany in 1933, German opponents of Nazism had look for exile on the American continent, forming complex political movements across the American continent. The presence of the Free German Movement and the Council for the Democratic German in Los Angeles has alerted the US authorities, especially because of evidence of their links with communism and their relations with political movements in Latin America. The purpose of this paper is to analyze the role of the Federal Bureau of Investigation (FBI) in investigating German anti-Nazi exile groups in California and south of the United States border in the context of World War II.