Va. Code Ann. § 15.2-612

The county manager shall be responsible to the board for the proper administration of all the affairs of the county which the board has authority to control. To that end he shall appoint all officers and employees in the county's administrative service, except as otherwise provided in this form of county organization and government, and except as he authorizes the head of a department or office responsible to him to appoint subordinates in such department or office. All appointments shall be based on the ability, training and experience of the appointees which are relevant to the work which they are to perform.