James Wormley "Jack" Jones was a World War I vet and former detective for the Washington D.C. Metropolitan Police Department. He'd also served as an instructor in explosives and bomb making during his time in the Army, which made him a perfect candidate for undercover work.
Jones was sworn in as the first African American FBI Special Agent in November 1919. He began working in a new division, the General Intelligence Division (GID), under future FBI director J. Edgar Hoover. The GID had been created in response to recent terrorist bombings, and Jones' expertise and undercover work was invaluable in fighting domestic terrorism. Jones retired from the FBI in 1923 after realizing he could no longer work under cover successfully.