1. Thanks to J. Edgar Hoover, FBI directors are now term-limited.

Hoover landed his first job with the Department of Justice in 1917 at just 22 and by 1924 had become the head of the FBI’s forerunner, the Bureau of Investigation. When Hoover died at 77, he had spent 48 years—62 percent of his life—at the helm of the powerful service. FBI directors are now limited to 10-year terms.

2. People are only removed from the Most Wanted list if they are captured, die, or if charges against them are dropped.

The FBI’s 10 Most Wanted Fugitives publicity campaign came about in 1950 when a reporter asked the agency for the names and descriptions of the “toughest guys” on its inventory of targets. The resulting article garnered so much attention that Hoover decided to begin issuing an official list. Since the program’s inception, 465 of the 494 criminals who made the top 10 have been apprehended or located.

3. The Federal Bureau of Investigation hasn’t always been known by that name.

When Attorney General Charles Bonaparte first recruited former detectives and Secret Service members for a new corps of federal investigators in 1908, he referred to it as a “special agent force.” Bonaparte’s successor, George Wickersham, dubbed it the Bureau of Investigation (BOI) the following year. In the spring of 1933, the BOI was incorporated into the newly formed Division of Investigation (DOI), which also included the unit that enforced Prohibition; after alcohol became legal again that December, the BOI became the DOI by default. The bureau was given its current name in 1935.

4. For Hoover, there were no women allowed.

In the 1920s, three women—Alaska Davidson, Jessie Duckstein and Lenore Houston—served as FBI agents. None were hired during the tenure of J. Edgar Hoover, who reportedly required all female employees to wear skirts or dresses and prohibited them from smoking at their desks (a “perk” enjoyed by men at the time). Shortly after Hoover’s death in 1972, the FBI Academy admitted two female agents-in-training: Susan Lynn Roley, a Marine Corps lieutenant, and Joanne Pierce, a former nun.

VIDEO — J Edgar Hoover the Spy

5. The FBI once spent two years investigating a song.

During the 1960s, analysts at the FBI’s cutting-edge laboratory spent more than two years investigating the lyrics of the Kingsmen’s hit pop song “Louie Louie.” As rumors swirled that the catchy but poorly recorded tune’s garbled verses contained pornographic language, concerned parents wrote to government authorities expressing their outrage. The FBI responded by subjecting various versions of the song to rigorous audio tests and producing a 120-page report that concluded it was “unintelligible at any speed.”

6. The Bureau had one of the world’s first art theft units.

After years of investigating art heists, in 2004 the FBI created a team tasked with solving that particular type of crime. Its members, who learn skills such as how to identify fakes, have recovered more than 2,600 stolen items worth nearly $150 million, from pre-Columbian artifacts to paintings by Rembrandt, Picasso and Matisse.

7. The FBI has its own lingo.

Not surprisingly, the FBI has historically used its own jargon, acronyms and abbreviations, some of which have leaked to the public. For instance, “brick agents” are investigators who work the streets, an “UNSUB” is an unknown subject, “Bucars” are the vehicles used by the agency and “Betty Bureau” refers to a female support employee who has worked at the FBI for her entire career. Meanwhile, critics of the bureau have their own nicknames for the FBI; other law enforcement officials allegedly joke that the initials stand for “Famous But Incompetent.”

8. The FBI once investigated ESP.

In the late 1950s, the FBI looked into whether extrasensory perception (ESP) could be used as an espionage tool, according to files declassified by the agency in April 2011. One agent wrote in a memo, “There is no limit to the value which could accrue to the FBI, complete and undetectable access to mail, visual access to buildings. The possibilities are unlimited.” In 1960 the bureau gave up after finding no scientific support for its potential.

9. Now one of the largest crime laboratories in the world, the FBI Laboratory started out small.

In fact, in 1932 it was a one-man operation housed in a single room that doubled as a smoking lounge. Its lone technician, Special Agent Charles Appel, used a borrowed microscope, a wiretapping kit and basic chemicals to analyze handwriting and examine crime scene evidence. Within a few years additional experts joined the team and the FBI built a state-of-the-art facility for them. The FBI Laboratory currently employs 500 scientists and provides forensic services to state, local and federal agencies.