Va. Code § 15.2-636
The board shall require an annual audit of the books of every county officer who handles public funds to be made by an accountant who is not a regular officer or employee of the county and who is qualified by training and experience. An audit made by the Auditor of Public Accounts under the provisions of law may be considered as having satisfied the requirements of this paragraph.
Either the board or the manager may at any time order an examination or audit of the accounts of any officer or department of the county government. Upon the death, resignation, removal or expiration of the term of any county officer, the director of finance shall cause an audit and investigation of the accounts of such officer to be made and shall report the results to the manager and the board. In case of the death, resignation or removal of the director of finance, the board shall cause an audit to be made of his accounts. If as a result of any such audit, an officer is found indebted to the county, the board shall proceed forthwith to collect such indebtedness.
Va. Code § 15.2-636