The general assembly shall annually appropriate any sum or sums that it may deem necessary for the payment of the salaries of any clerical assistance that may be deemed necessary and for the payment of office expenses and other actual expenses incurred by the public defender in the performance of his or her duties; and the controller is authorized and directed to draw his or her orders upon the general treasurer for the payment of the sum or sums, or as much of the sum or sums as may from time to time be required, upon receipt by him or her of proper vouchers approved by the public defender.