FBI Director Robert Mueller has suggested that the terror attacks will bring with them major changes for the bureau, including a shift from investigation to prevention.

It wouldn't be the first time that social and political upheaval has led to changes for the bureau. Here's a selected chronology:

_1909: The spread of the railways and the introduction of the automobile make it easier for criminal fugitives to travel between states, leading President Theodore Roosevelt to establish the Bureau of Investigation as a federal law enforcement agency.

_1930s: Organized crime runs rampant, persuading Congress to overcome states' resistance and ``federalize'' a number of crimes. The kidnapping of the Lindbergh baby leads Congress to make kidnapping a federal offense.

_1936: The growth of domestic interest in communism and fascism leads President Franklin D. Roosevelt to authorize the investigation of ``subversives.''

_1940s: The Nazi threat prompts the establishment of the first ``legats,'' FBI agents assigned to overseas embassies as ``legal attaches.''

_1946: The threat from Russia's Joseph Stalin pervades American political thinking, and Congress passes the Atomic Energy Act, which includes a mandate to the FBI to ``determine the loyalty of individuals'' with access to nuclear data. To this day, the FBI runs background checks on senior government appointments.

_1960s: Congress passes civil rights acts authorizing the bureau to pursue civil rights violators. The FBI uses the mandate to circumvent white law enforcement officers and juries who are sympathetic to violent racists.

_1970s: The FBI makes white-collar crime its ``third national priority,'' after counterintelligence and organized crime. It recruits accountants to become agents.

_1982: The rise of terrorism leads the FBI to make counterterrorism a ``fourth national priority.''

_1991: At the dawn of the Internet age, the ``National Security Threat List'' is aimed at protecting U.S. information and technologies.

__

Source: Official FBI history, http://www.fbi.gov/fbinbrief/historic/history/historymain.htm