James Amos worked for the Department of the Interior, the Customs Office, and as an investigator for the Burns International Detective Agency before becoming President Theodore Roosevelt's bodyguard and attendant–a job he held for 12 years. Roosevelt was so impressed–particularly with Amos' keen shooting skills–that he was one of Amos' references when he applied to be a special agent with the FBI in 1921. Amos was one of only a handful of African American special agents working at the Bureau of Investigation, as the FBI was known then-the first known African American special agent, James Wormley Jones, joined in 1919. Amos would become the longest-serving African American agent in the pre-modern Bureau, serving the FBI for 32 years.
Amos worked some of the biggest cases in FBI history, including the Duquesne Nazi spy ring, the Louis "Kepke" Buchalter gang-a band of professional hit men known as "Murder, Inc.," and the "Tri-State Gang," who were charged with multiple murders-and Marcus Garvey and his Black Star Steamship Company, which defrauded African Americans by falsely promising paid passages to Africa. Much of his work involved infiltrating "subversive elements" to collect information for the FBI. He retired in 1953, having served his country honorably and paved the way for other African Americans at the FBI.