40 ILCS 5/2-147
The State Comptroller in drawing salary warrants on payroll vouchers for members shall draw such warrants to participants for the salary specified less the member contributions to be deducted, as certified in the vouchers, and shall draw a warrant to the system for the total of the contributions so withheld on each such payroll voucher. The warrant drawn to the system, and the additional copy of the payroll, shall be transmitted immediately to the secretary.
The Comptroller shall draw warrants or prepare direct deposit transmittals upon the State Treasurer payable from the funds of this system for purposes of this Article upon the presentation of vouchers approved by the secretary in accordance with resolutions of the board, and in the exercise of the investment authority, upon presentation of vouchers approved by the director of the Illinois State Board of Investment in accordance with the order and direction of said board.
40 ILCS 5/2-147