Question: What does the acronym of the agency that employed Melvin Purvis stand for?

full_context: Document 1: Federal Bureau of Investigation: The FBI has maintained files on numerous people, including celebrities such as Elvis Presley, Frank Sinatra, John Denver, John Lennon, Jane Fonda, Groucho Marx, Charlie Chaplin, the band MC5, Lou Costello, Sonny Bono, Bob Dylan, Michael Jackson, and Mickey Mantle. The files were collected for various reasons. Some of the subjects were investigated for alleged ties to the Communist party (Charlie Chaplin and Groucho Marx), or in connection with antiwar activities during the Vietnam War (John Denver, John Lennon, and Jane Fonda). Numerous celebrity files concern threats or extortion attempts against them (Sonny Bono, John Denver, John Lennon, Elvis Presley, Michael Jackson, Mickey Mantle, Groucho Marx, and Frank Sinatra).
Document 2: Federal Bureau of Investigation: Although many of FBI's functions are unique, its activities in support of national security are comparable to those of the British MI5 and the Russian FSB. Unlike the Central Intelligence Agency (CIA), which has no law enforcement authority and is focused on intelligence collection overseas, FBI is primarily a domestic agency, maintaining 56 field offices in major cities throughout the United States, and more than 400 resident agencies in lesser cities and areas across the nation. At an FBI field office, a senior-level FBI officer concurrently serves as the representative of the Director of National Intelligence.
Document 3: Central Intelligence Agency: The CIA had different demands placed on it by the different bodies overseeing it. Truman wanted a centralized group to organize the information that reached him, the Department of Defense wanted military intelligence and covert action, and the State Department wanted to create global political change favorable to the US. Thus the two areas of responsibility for the CIA were covert action and covert intelligence. One of the main targets for intelligence gathering was the Soviet Union, which had also been a priority of the CIA's predecessors.
Document 4: Near East: The Central Intelligence Agency (CIA) is a quasi-independent agency of the United States Government. It appears to have multiple leadership. On the one hand its director is appointed by the president. It plays a significant role in providing the president with intelligence. On the other hand, Congress oversees its operations through a committee. The CIA was first formed under the National Security Act of 1947 from the army's Office of Strategic Services (OSS), which furnished both military intelligence and clandestine military operations to the army during the crisis of World War II. Many revisions and redefinitions have taken place since then. Although the name of the CIA reflects the original advised intent of Presidents Franklin D. Roosevelt and Harry S. Truman, the government's needs for strategic services have frustrated that intent from the beginning. The press received by the agency in countless articles, novels and other media have tended to create various popular myths; for example, that this agency replaced any intelligence effort other than that of the OSS, or that it contains the central intelligence capability of the United States. Strategic services are officially provided by some 17 agencies called the Intelligence Community. Army intelligence did not come to an end; in fact, all the branches of the Armed Forces retained their intelligence services. This community is currently under the leadership (in addition to all its other leadership) of the Office of the Director of National Intelligence.
Document 5: Federal Bureau of Investigation: Despite its domestic focus, the FBI also maintains a significant international footprint, operating 60 Legal Attache (LEGAT) offices and 15 sub-offices in U.S. embassies and consulates across the globe. These overseas offices exist primarily for the purpose of coordination with foreign security services and do not usually conduct unilateral operations in the host countries. The FBI can and does at times carry out secret activities overseas, just as the CIA has a limited domestic function; these activities generally require coordination across government agencies.
Document 6: Federal Bureau of Investigation: During the September 11, 2001 attacks on the World Trade Center, FBI agent Leonard W. Hatton Jr. was killed during the rescue effort while helping the rescue personnel evacuate the occupants of the South Tower and stayed when it collapsed. Within months after the attacks, FBI Director Robert Mueller, who had been sworn in a week before the attacks, called for a re-engineering of FBI structure and operations. He made countering every federal crime a top priority, including the prevention of terrorism, countering foreign intelligence operations, addressing cyber security threats, other high-tech crimes, protecting civil rights, combating public corruption, organized crime, white-collar crime, and major acts of violent crime.
Document 7: Dillinger (1973 film): Retired FBI Agent Clarence Hurt, one of the agents involved in the final shootout with Dillinger, was the film's technical advisor. The film includes documentary imagery and film footage from the era. It includes a verbal renouncing of gangster films written by FBI chief J. Edgar Hoover: he was scheduled to read it for the film, but died before it started production. Hoover's text is read at the film's close by voice actor Paul Frees.
Document 8: Federal Bureau of Investigation: The Federal Bureau of Investigation (FBI) is the domestic intelligence and security service of the United States, which simultaneously serves as the nation's prime federal law enforcement organization. Operating under the jurisdiction of the U.S. Department of Justice, FBI is concurrently a member of the U.S. Intelligence Community and reports to both the Attorney General and the Director of National Intelligence. A leading U.S. counterterrorism, counterintelligence, and criminal investigative organization, FBI has jurisdiction over violations of more than 200 categories of federal crimes.
Document 9: Federal Bureau of Investigation: J. Edgar Hoover served as Director from 1924 to 1972, a combined 48 years with the BOI, DOI, and FBI. He was chiefly responsible for creating the Scientific Crime Detection Laboratory, or the FBI Laboratory, which officially opened in 1932, as part of his work to professionalize investigations by the government. Hoover was substantially involved in most major cases and projects that the FBI handled during his tenure. After Hoover's death, Congress passed legislation that limited the tenure of future FBI Directors to ten years.
Document 10: Federal Bureau of Investigation: The FBI has been frequently depicted in popular media since the 1930s. The bureau has participated to varying degrees, which has ranged from direct involvement in the creative process of film or TV series development, to providing consultation on operations and closed cases. A few of the notable portrayals of the FBI on television are the 1993-2002 series The X-Files, which concerned investigations into paranormal phenomena by five fictional Special Agents and the fictional Counter Terrorist Unit (CTU) agency in the TV drama 24, which is patterned after the FBI Counterterrorism Division. The 1991 movie Point Break is based on the true story of an undercover FBI agent who infiltrated a gang of bank robbers. The 1997 movie Donnie Brasco is based on the true story of undercover FBI agent Joseph D. Pistone infiltrating the Mafia.
Document 11: Federal Bureau of Investigation: In 2005, fugitive Puerto Rican Nationalist leader Filiberto Ojeda Ríos died in a gun battle with FBI agents in 2005 in what some charged was an assassination.[citation needed] Puerto Rico Governor Aníbal Acevedo Vilá criticized the FBI assault as "improper" and "highly irregular" and demanded to know why his government was not informed of it. The FBI refused to release information beyond the official press release, citing security and agent privacy issues. The Puerto Rico Justice Department filed suit in federal court against the FBI and the US Attorney General, demanding information crucial to the Commonwealth's own investigation of the incident. The case was dismissed by the U.S Supreme Court. Ojeda Rios' funeral was attended by a long list of dignitaries, including the highest authority of the Roman Catholic Church in Puerto Rico, Archbishop Roberto Octavio González Nieves, ex-Governor Rafael Hernández Colón, and numerous other personalities.
Document 12: Federal Bureau of Investigation: The FBI's chief tool against organized crime is the Racketeer Influenced and Corrupt Organizations (RICO) Act. The FBI is also charged with the responsibility of enforcing compliance of the United States Civil Rights Act of 1964 and investigating violations of the act in addition to prosecuting such violations with the United States Department of Justice (DOJ). The FBI also shares concurrent jurisdiction with the Drug Enforcement Administration (DEA) in the enforcement of the Controlled Substances Act of 1970.
Document 13: Federal Bureau of Investigation: The FBI often works in conjunction with other Federal agencies, including the U.S. Coast Guard (USCG) and U.S. Customs and Border Protection (CBP) in seaport and airport security, and the National Transportation Safety Board in investigating airplane crashes and other critical incidents. Immigration and Customs Enforcement Homeland Security Investigations (ICE-HSI) has nearly the same amount of investigative man power as the FBI, and investigates the largest range of crimes. In the wake of the September 11 attacks, then-Attorney General Ashcroft assigned the FBI as the designated lead organization in terrorism investigations after the creation of the U.S. Department of Homeland Security. ICE-HSI and the FBI are both integral members of the Joint Terrorism Task Force.
Document 14: Central Intelligence Agency: Unlike the Federal Bureau of Investigation (FBI), which is a domestic security service, CIA has no law enforcement function and is mainly focused on overseas intelligence gathering, with only limited domestic collection. Though it is not the only U.S. government agency specializing in HUMINT, CIA serves as the national manager for coordination and deconfliction of HUMINT activities across the entire intelligence community. Moreover, CIA is the only agency authorized by law to carry out and oversee covert action on behalf of the President, unless the President determines that another agency is better suited for carrying out such action. It can, for example, exert foreign political influence through its tactical divisions, such as the Special Activities Division.
Document 15: Federal Bureau of Investigation: During the 1950s and 1960s, FBI officials became increasingly concerned about the influence of civil rights leaders, whom they believed had communist ties or were unduly influenced by them. In 1956, for example, Hoover sent an open letter denouncing Dr. T.R.M. Howard, a civil rights leader, surgeon, and wealthy entrepreneur in Mississippi who had criticized FBI inaction in solving recent murders of George W. Lee, Emmett Till, and other blacks in the South. The FBI carried out controversial domestic surveillance in an operation it called the COINTELPRO, which was short for "COunter-INTELligence PROgram." It was to investigate and disrupt the activities of dissident political organizations within the United States, including both militant and non-violent organizations. Among its targets was the Southern Christian Leadership Conference, a leading civil rights organization with clergy leadership.
ground_truth: Federal Bureau of Investigation
sub_queries: Melvin Purvis >> employer Answer: FBI
What does FBI stand for? Answer: Federal Bureau of Investigation