The purpose of the Bureau of Investigation was to investigate the crimes "of national banking, bankruptcy, naturalization, anti-trust, peonage and land fraud (www.fbi.gov/history)." The Bureau had limited jurisdiction over crime until June 1910, when the Mann Act was passed. This law made it a violation of state law "to transfer women across state lines for immoral purposes", it also helped the FBI investigate crimes that went across state lines. In 1912, A. Bruce Bielaski became Chief of the Bureau. During this time the number of special agents grew to 300.
With the entry of the United States into World War I in April 1917,the Bureau of Investigation was ordered by the government to investigate the crimes of espionage, selective service and sabotage. The Bureau also focused its efforts on controlling smuggling and obtaining intelligence around the Mexican border. William J. Flynn, became Chief of the Bureau using the title Director of the Bureau of Investigations. The National Motor Vehicles Theft Act of 1919 was passed during this time, giving the Bureau another passage to prosecute criminals across state lines.
The end of the war brought about another phase of the Bureau. This was the time known as the "lawless years," where gangsters ruled the streets, and prohibition divided this country. Furthermore, the Ku Klux Klan was again reborn to neutralize the economic gains by African Americans after the war. In 1924, Edgar Hoover was selected to head the Bureau of Investigation. When he became head there were 650 employees, 441 special agents and 30 field offices. Hoover reformed the agency many times, stressing a need for professionalism. He began by firing many unqualified agents. In January 1928, he also created the training course for agents and established that you must be between 25-35 to apply to the program. Another major upgrade to the Bureau, and law enforcement as a whole, was the creation of the National Division of Identification. The primary method of identification that is still being used today, was fingerprinting.
The Stock Market crash of 1929 and the great depression caused higher crime rates and fear in the public. To gain public support for his programs, Hoover brought the agency's message to the people. For example, in 1932 the FBI published Fugitives Wanted by Police, known today as the FBI Law Enforcement Bulletin. Furthermore, the agency gained much more respect from the public after investigating the kidnapping of the Lindberg baby, and trying to put an end to gangsters. These led to federal kidnapping stature as well as laws increasing the Bureaus jurisdiction across state lines. During this period the Bureau increased to 42 field offices and 654 special agents. In July 1932, it was renamed the US Bureau of Investigation, and in 1935 it became the Federal Bureau of Investigation. Another major accomplishment was the establishment of the Technical Laboratory in 1932. By 1935 the FBI began training police officers at the FBI National Academy and by the 1940's it was training people all over...