Mueller was born on August 7, 1944, at Doctors Hospital in the New York City borough of Manhattan, the first child of Alice C. Truesdale (1920–2007) and Robert Swan Mueller Jr. (1916–2007).

The Mueller investigation took over the FBI's investigation, Crossfire Hurricane. The Mueller investigation's scope included allegations of "links and/or coordination" between the Russian government and individuals associated with the Trump campaign.

J. Edgar Hoover led the FBI for nearly a half-century, from 1924 until 1972. Under Director Hoover, the Bureau grew in responsibility and importance, becoming an integral part of the national government and an icon in American popular culture.

Since 1976, directors serve a ten-year term unless they resign, die, or are removed, but in practice, since Hoover, none have served a full ten years, except Mueller who served twelve years with the leave of Congress. The director of the FBI can be removed from office by the president of the United States.