Portrait of a Special Agent Showing his ID Card

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Introduction to How the FBI Works

The Federal Bureau of Investigation is the most powerful government agency in the United States. Some call it the largest law enforcement agency in the world. In its 100-year history, the agency has been at the heart of several infamous cases -- some successful, some controversial. In the age of terrorism, the FBI is as complicated and powerful as ever.

In this article, we'll find out what the FBI does, how it started, and how you can become an FBI agent. We'll take a look at some of the tools and techniques used by the FBI, and we'll learn about J. Edgar Hoover, the man who molded the Bureau into a powerful crime-solving agency.

­The FBI is the investigative arm of the U.S. Department of Justice, and its specific mission is constantly evolving. Currently, the FBI's focus is on stopping terrorism, corruption, organized crime, cyber crime and civil rights violations, as well as investigating serious crimes such as major thefts or murders. They also assist other law enforcement agencies when needed. Crimes that specifically fall under FBI jurisdiction include those in which the criminal crossed state lines, violations of federal controlled substance laws, and other violations of federal laws.

According to its Web site:

The official mission of the FBI is to uphold the law through the investigation of violations of federal criminal law; to protect the United States from foreign intelligence and terrorist activities; to provide leadership and law enforcement assistance to federal, state, local, and international agencies; and to perform these responsibilities in a manner that is responsive to the needs of the public and is faithful to the Constitution of the United States.

To dispel some myths about the FBI, here are some things that it doesn't do:

  • It is not a national police force; state and local law enforcement agencies are not subservient to the FBI. It's simply a different jurisdiction for different kinds of crimes.
  • It doesn't "take over" cases from local agencies. If a crime partly involves FBI jurisdiction, or if it is serious enough to require FBI involvement, then the FBI forms a task force in which agents will work closely with state and local police.
  • The FBI does not prosecute cases. It provides investigative information to United States attorneys, who then use that information to decide whether to prosecute.

FBI agents can carry firearms, and their use is restricted by the same rules that restrict all other law enforcement offices in the U.S. Deadly force can only be used when necessary to prevent death or injury to the agent or others. Agents cannot wiretap suspects (use electronic means to listen in on telephone conversations) without receiving a court order. To get a court order, they have to prove probable cause that the suspect is engaged in an illegal activity, and that a wiretap will help them gain crucial information. A federal judge must approve and monitor the tap. Wiretapping without a court order is a felony.

FBI Director Robert S. Mueller, III

Image courtesy FBI

Structure of the FBI

The J. Edgar Hoover FBI Building

Image courtesy CIA

The FBI is part of the U.S. Department of Justice, which is headed by the U.S. Attorney General. The FBI exists under the Attorney General's authority to create investigative agents for the enforcement of federal laws (Sections 533 and 534, Title 28 of the U.S. Code). However, the Attorney General doesn't exercise direct authority over the FBI itself -- that's the job of the Inspector General. Prior to 2002, the Inspector General could investigate the FBI, but only with the permission of the Attorney General. In the wake of several scandals in 2001, including the revelation that FBI agent Robert Hanssen had been selling U.S. secrets to the Soviets for 15 years, Congress gave the Inspector General more oversight power [ref].

The President appoints the director of the FBI for a 10-year term. The current director is Robert S. Mueller, III. There are several deputy directors beneath him, and an executive assistant director heads each of the 11 divisions of the FBI. These divisions generally coincide with a type of crime the FBI investigates. For example, there is a counterterrorism division, a criminal investigation division and an information technology division.

The FBI is headquartered in the J. Edgar Hoover Building in Washington, D.C. Opened in 1974, the massive bunker-like building houses the director, most department heads and the world-famous FBI Crime Lab. (The FBI building tour is currently closed for renovations, but tours are scheduled to resume in Spring 2007.) FBI Field offices are located in most major cities -- there are 56 in total. A Special Agent in Charge heads each field office. An assistant director heads exceptionally large field offices in New York and Los Angeles. In addition, the FBI has about 400 resident agencies in smaller cities or other areas where an FBI presence is required.

The FBI's Organization

As of March 31, 2006, the FBI employed more than 30,000 people, comprising 12,515 agents, and 17,485 support personnel, lab technicians and administrators. In the past, the FBI was considered an unfriendly place for women and minorities. In 1972, the FBI did not have a single female agent, and only a small percentage were minorities [ref]. Today, more than 13,000 FBI employees are women, with 7,691 minorities and over 1,000 people with disabilities [ref].

FBI funding is part of the Department of Justice and comes from the overall federal budget. In 2003, the FBI's total budget was $4.298 billion [ref].

Next, we'll learn about the history of the FBI.


FBI Nomenclature

  • July 26, 1908 - Created with no specific name; referred to as Special Agent Force
  • March 16, 1909 - Bureau of Investigation
  • July 1, 1932 - U.S. Bureau of Investigation
  • August 10, 1933 - Division of Investigation (The Division also included the Bureau of Prohibition)
  • July 1, 1935 - Federal Bureau of Investigation

FBI History

The Department of Justice has always had the power to investigate federal crimes, but it didn't always have the means to do so. In the 19th century, government agencies often hired private detective firms such as the Pinkertons to solve crimes [ref]. In 1908, Illegal land sales in the western United States angered President Theodore Roosevelt, who then gave Attorney General Charles J. Bonaparte the authority to create a small bureau of detectives to investigate these crimes. By 1909, they were given an official name: The Bureau of Investigation.

Initially, very few crimes were under the Bureau's jurisdiction. Land fraud, national bank scams, anti-trust crimes and criminals who crossed state lines were under the Bureau's purview. Over the next decade, new laws expanded the scope of the federal government to investigate national crimes, and the number of agents increased as well. During World War I, agents focused on stopping espionage and sabotage, and cracking down on men who avoided the draft. By the 1920s, there were more than 300 agents and 300 support personnel operating a growing number of field offices [ref].

Until the early 1920s, unprofessional agents who were poorly trained and unqualified for their jobs plagued the Bureau of Investigation. Politics was a strong influence, and agents could be easily bribed to overlook crimes. Agents sometimes gathered incriminating information to discredit political opponents [ref, ref]. All that began to change in 1924, when Attorney General Harlan Fiske Stone elevated 29-year-old Assistant Director J. Edgar Hoover to the office of Director. Hoover immediately began reviewing procedures and agent records. He personally reviewed every agent's file, and was amazed at how many agents were on staff solely because of political connections or favors. He fired more than 100 of them within a few months [ref]. Then, Hoover raised the standards for hiring new agents, requiring college educations and law enforcement experience. He created rules and regulations for agent conduct and investigative procedure, ensuring that Bureau activity would be uniform across the nation. As Hoover put it, "We all should be concerned with only one goal -- the eradication of crime."

Hoover was also responsible for many reforms in the field of criminal investigation. He created the FBI Crime Lab in 1932, and opened a training academy in 1935, the same year the Bureau became the Federal Bureau of Investigation. This academy trained FBI agents as well as numerous local and state police officers. Another Hoover innovation was the Ten Most Wanted list. Created in 1950, this list provides photos and information on the ten fugitives (in no particular order) the FBI most wants to catch, and is posted in public places such as post offices. As of 2002, 458 people had been shown on the list, and 429 had been captured. Today, the Ten Most Wanted list is available online.

Through World War II and into the Cold War, the FBI continued to take on new duties under Hoover's guidance. The Bureau investigated German and Japanese spies during the war and rooted out Communists in the post-war years. The FBI's priorities changed once again in the wake of the 9/11 attacks; now, counterterrorism is a top priority. The Bureau tracks known terrorists and cooperates with other agencies, such as the CIA, and intelligence and law enforcement agencies from other countries to gather information. Unlike many other government agencies, the FBI was not folded into the Department of Homeland Security -- it continues to operate within the Department of Justice.

J. Edgar Hoover

FBI Director J. Edgar Hoover amassed a lot of political power during his tenure -- much of it acquired by using the FBI to intimidate and gather incriminating information about his opponents. In his exposé of FBI corruption, "The Bureau," author Diarmuid Jeffreys wrote, "It was rumored that the director [Hoover] had detailed information about the sexual, political, and financial indiscretions of some of the country's most powerful and famous people and that he had used this information to blackmail his way to power and influence." Hoover remained in his position as FBI Director until his death, although several presidents considered firing him.

After Hoover's death in 1972, some of his personal files were transferred to former agent Mark Felt, the man who was later revealed as "Deep Throat" in the Watergate scandal. The files contained gossip on entertainers, intimidating letters sent to Martin Luther King, Jr., allegations that certain political candidates were homosexual, and documentation of illegal FBI wiretapping [ref]. Hoover's controversial (and mostly illegal) COINTELPRO operation targeted so-called radical groups that protested the Vietnam War or worked for civil rights, alongside other groups that promoted violent overthrow of the government.

At times, Hoover's drive to root out subversives within the United States bordered on paranoia. In a 1966 magazine interview, he proclaimed that American was threatened by "a new style in conspiracy -- conspiracy that is extremely subtle and devious and hence difficult to understand. A conspiracy reflected by questionable moods and attitudes, by unrestrained individualism, by nonconformism in dress and speech, even by obscene language, rather than by formal membership in specific organizations" [ref].

Both in life and in death, persistent rumors pegged Hoover as a deeply closeted homosexual and cross-dresser, and that proof was in the hands of the Mafia. However, solid evidence of these allegations has never been found.

Next, we'll learn about some of the investigative methods and tools used by the FBI.

Image courtesy FBI

FBI Divisions and Methods

Because the FBI's mission continues to evolve and has such a wide scope, it has developed many different divisions to process information and handle incidents. A few of these include the Criminal Justice Information Services Division (CJIS), the Laboratory Division (or "Crime Lab"), the Behavioral Analysis Unit and the Hostage Rescue Team. Let's look at each of these divisions in detail.

The Criminal Justice Information Services Division (CJIS) is the largest division within the FBI. This makes sense because the collection, analysis and comparison of crime scene data is some of the FBI's most important work. The CJIS comprises several programs, including the Integrated Automated Fingerprint Identification System (IAFIS). The IAFIS contains the fingerprints of more than 47 million subjects and is the largest database of its kind in the world. The CJIS also includes the National Crime Information Center (NCIC). It stores detailed information on crimes committed across the United States, regardless of which organization originally investigated the crime. Law enforcement agencies at the national, state and local levels can access both the IAFIS and the information contained in the NCIC, helping them identify criminals who may move from place to place by spotting patterns and similarities between crimes.

Law enforcement agencies can also use the services of the Laboratory Division. As one of the largest forensic laboratories in the world, the FBI Crime Lab has conducted more than one million forensic examinations and pioneers new techniques in forensic analysis. The laboratory conducts forensic investigations on all types of physical evidence, including DNA, blood, hair, fibers, latent fingerprints, documents, handwriting and firearms. Law enforcement agencies can also receive training from the Lab's Forensic Science Research and Training Center (FSRTC) at the FBI Academy. Laboratory examiners provide expert testimony in court cases that deal with forensic evidence.

The FBI has been a pioneer in the technique of criminal investigative analysis (sometimes called "profiling"), conducted by the staff of the Behavioral Analysis Unit. According to the division's Web site, criminal investigative analysis "is a process of reviewing crimes from both a behavioral and investigative perspective." Trained profilers look at the evidence and circumstances surrounding a crime or series of crimes and create a profile that describes various aspects of the suspect's personality. Gender, age, level of education, types of jobs and other elements can narrow investigations and help agents prioritize leads. Geographical profiling helps as well -- in this technique, profilers feed information about the locations of crimes into a computer, which creates an "area of interest" for investigators to focus on [ref]. Profilers require about a year of in-depth training, and an academic background in psychology or another social science is helpful. However, the most important trait of an FBI profiler is extensive experience working on investigations.

The FBI also has one of the top hostage rescue teams in the world -- the Hostage Rescue Team, a part of the Tactical Support Branch of the Critical Incident Response Group. Initially, the HRT was a tactical rescue unit outfitted like a SWAT team. Their job was to end a hostage situation with the use of force. The Hostage Negotiation Unit was separate, and was supposed to try resolving hostage situations peacefully before the HRT went in. An adversarial relationship grew between the two units, culminating in the controversial Ruby Ridge incident. In 1992, U.S. Marshalls were in a standoff with a heavily armed family in rural Idaho. The FBI went in, but the HRT acted contrary to advice from experienced negotiators and ordered snipers to fire on the family before the negotiators had a chance to end things peacefully. Snipers killed the mother of the family [ref]. In response to this and other incidents, the FBI created the Critical Incident Response Group, which combines the Crisis Negotiation Unit and the HRT into a single group with a single commander.

Following September 11, 2001, FBI Director Richard Mueller ordered operational and organizational changes to support changes in the FBI's focus: "prevention of terrorist attacks, countering foreign intelligence operations against the U.S., and addressing cybercrime-based attacks and other high-technology crimes" [ref]. The organization is also working on technological upgrades to meet these changes and provide stronger support to federal, state and local agencies.

For lots more information on the FBI and related topics, check out the links on the next page.

Lots More Information


  • Breuer, William B. "J.Edgar Hoover and His G-Men." Praeger Publishers, 1995. 0275949907.
  • De Capua, Sarah. "The FBI." Children's Press, 2002. 0516226916.
  • Hargrove, Jim. "The Story of the FBI." Children's Press, 1988. 0516447335.
  • January, Brendan. The FBI. Franklin Watts, 2003. 0531166015.
  • Jeffreys, Diarmuid. "The Bureau." Replica Books, 2001. 0735101361.
  • MacFarland, Margo. "House and Senate conferees agree on FBI oversight." GovExec.com, September 20, 2002. http://www.govexec.com/dailyfed/0902/092002njns1.htm
  • McCrary, Gregg. "The Maryland and D.C. shootings: Former FBI profiler Gregg McCrary." USA Today, October 7, 2002. http://www.usatoday.com/community/chat/2002-10-07-mccrary.htm
  • "Wanted by the FBI." http://www.fbi.gov/wanted.htm
  • "Objective of the Firearms Training Unit." https://www.fbijobs.gov/PreQuanticoKit/chapter04.htm
  • FBI FAQ. http://www.fbi.gov/aboutus/faqs/faqsone.htm
  • FBI Facts and Figures. http://www.fbi.gov/priorities/priorities.htm
  • The FBI Academy. http://www.fbi.gov/hq/td/academy/academy.htm
  • Federal Bureau of Investigation: History. http://www.fas.org/irp/agency/doj/fbi/fbi_hist.htm
  • FBI Laboratory. http://www.fbi.gov/hq/lab/labhome.htm