Aaron Zebley was Robert Mueller's deputy and was by his side for every major decision. Prior to working in the special counsel's office, Zebley served in multiple roles at the US Department of Justice and the FBI, including FBI chief of staff, senior counselor in the Department of Justice's National Security Division, assistant US attorney for the Eastern District of Virginia, and as an FBI team leader and case agent in the 9/11 investigation. Zebley is in private practice in Washington, DC.

James Quarles was Mueller's senior counselor. A seasoned trial lawyer who has practiced for more than fifty years, Quarles primarily focuses on representing high-technology companies. Prior to his long career in private practice, Quarles served as an assistant special prosecutor on the Watergate Special Prosecution Force from 1973 to 1975.

Andrew Goldstein was one of Mueller's lead prosecutors investigating obstruction of justice and Russian interference. Prior to working in the special counsel's office, Goldstein served as chief of the public corruption unit at the US attorney's office for the Southern District of New York, where he prosecuted numerous high-profile cases. Goldstein is a former staff writer at Time, and currently chairs the white-collar defense and investigations practice at Cooley LLP.