Va. Code § 15.2-635
The clerk of the circuit court, the attorney for the Commonwealth and the sheriff shall be selected in the manner and for the terms, and vacancies in such office shall be filled, as provided by general law.
The clerk of the circuit court shall be clerk of the board of supervisors unless the board designates some other person for this purpose. The clerk of the board shall exercise the powers conferred and perform the duties imposed upon such officer by general law and shall be subject to the obligations and penalties imposed by general law. He shall also perform such other duties as the board imposes upon him.
The directors or heads of all other departments of the county shall be appointed by the county manager. The county manager may, with the board's consent, act as the director or head of one or more departments of the county, provided he is otherwise eligible to head such department or departments and, in the case of those officers whose appointments must be approved, his appointment is likewise approved.
In case of the absence or disability of any officer, other than the attorney for the Commonwealth, the clerk of the circuit court and the sheriff, which offices shall be filled as prescribed by general law, the county manager or other appointing power may designate some responsible person to perform the duties of the office.
Va. Code § 15.2-635