The board may appoint a county auditor for the audit and review of county agencies and county-funded functions. The county auditor shall have the power to make performance reviews of operations of county agencies or county-funded programs to ascertain that sums appropriated are expended for the purposes for which such appropriations were made and to evaluate the effectiveness of those agencies and programs. The county auditor shall make such special studies and reports as the board directs. The board may provide staff assistance to the county auditor that may be independent of the administrative staff of the county. The county auditor and any such staff shall be hired on the basis of merit and shall be paid in conformity with existing pay scales. The county auditor shall serve at the pleasure of the board, and if removed, such removal shall not be subject to review by any other employee, agency, board, or commission of the county or under the grievance procedure adopted pursuant to § 15.2-1506.