Lieutenant Colonel Robert “Bob” Mosier serves as Chief Deputy, Administrative and Corrections Bureau, for the Loudoun County Sheriff's Office (LCSO) and joined the LCSO in 2023.
He has more than 40 years of experience in federal, state, and local law enforcement, and in the private sector, most recently as the Secretary of Public Safety and Homeland Security for Virginia Governor Glenn Youngkin, where he also served on the Virginia Substance Abuse Services Council and Criminal Justice Services Board. He was elected twice as Sheriff of Fauquier County, Virginia, and previously served as Commander of Special Operations, the Patrol Division, and the Criminal Investigations Division there. He also worked for the U.S. Dept. of State and U.S. Dept. of Defense in support of international policing, and as Vice President of Investigations for the International Justice Mission.
Lieutenant Colonel Mosier earned a bachelor’s degree in criminal justice from Aspen University, an associate degree in special police operations from NOVA Community College, and a professional development certification from the Virginia Sheriff’s Institute at the L. Douglas Wilder School of Government and Public Affairs.