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 lead U.S. counterterrorism, counterintelligence, and criminal investigative organization, FBI has jurisdiction over violations of more than 200 categories of federal crime.
Although many of FBI's functions are unique, its activities in support of national security are comparable to that 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 (DNI).
After a drone strike that killed 18 Secret Service agents and nearly killed President Allan Trumbull, the FBI were sent to investigate the scene where they found false evidence left by Salient Global that revealed Mike Banning was behind the attack and was getting support from the Russian government.
Afterwards, Mike was arrested and transported to a detention facility, but his escort were ambushed by Salient Global on the way there. They later investigated the scene and loaded the state marshals into body bags. The FBI also noticed that the VIN plates on the SUV's were stripped.
The FBI caught another lead on Mike when they traced a phone call that pinpointed him to a gas station. After a brief police chase, Mike escaped again after crashing a stolen trailer truck. The next morning, the FBI went to the crash scene to see if they were any loose ends.
After killing several Salient Global operatives who were advancing on his father's residence in West Virginia, Mike led the FBI to the bodies so they acquire proof that Mike was really being set up after all.
Thompson and Ramirez later traveled to the Salient Global Facility to confront Wade Jennings, but she and Ramirez were shot dead. While Thompson was killed, her efforts to exonerate Mike succeeded and uncovered evidence that Vice President Martin Kirby was the real mastermind behind the assassination plot.
The FBI was later deployed to St. Matthew's Hospital along with the National Guard, Hostage Rescue Team, and SWAT in response to the gunfight between the Secret Service and Salient Global. After the crisis, they dropped all charges against Mike as well as its allegations with Russia in Trumbull's attempted assassination.