According to CNN in November 2016, shortly after the FBI begins its Clinton email investigation on July 10, 2015, FBI Director James Comey decides to run the investigation from FBI headquarters in Washington, DC, instead of the New York office, which normally would be the proper jurisdiction, since the Clinton private email server had been located in Chappaqua, New York. CNN will report, “That decision anger[s] some in New York who thought it was headquarters’ interference into their case.”
Comey then mostly picks agents from the Washington, DC, field office to handle the investigation. He assigns the case “to the counterintelligence section, which investigates cases of alleged mishandling of classified information. It [gives] the added advantage of being a section with a reputation for few media leaks and being close enough for Comey to get personal almost-daily updates.”
Furthermore, all agents working on the case are required to sign an unusual non-disclosure agreement and also agree to be subject to random lie detector tests.
One unnamed senior official will later say, “We’re in the middle of one of the most vitriolic campaigns in American history, and we’re investigating one of the candidates for president. We had to get this right.” (CNN, 11/2/2016)