40 ILCS 5/19-106
The city treasurer, subject to the control and direction of the board of trustees hereinafter mentioned, shall be the custodian of said pension fund and shall secure and safely keep same and shall keep books and accounts concerning said funds in such manner as may be prescribed by said board of trustees, which said books and accounts shall always be subject to the inspection of said board of trustees, or any member thereof.
The city treasurer shall within 10 days after his election or appointment, execute a bond to the city, with good and sufficient securities, in such penal sum as the said board of trustees shall direct, and shall be conditioned for the faithful performance of the duties of said office, and that he will safely keep and well and truly account for all moneys belonging to said pension fund, and all interest thereon, which may come into his hands, as such treasurer, and on the expiration of his term of office, or upon his retirement therefrom for any cause, he will surrender and deliver over to his successor all unexpended moneys, with such interest as he may have received thereon, and all property which may come into his hands as treasurer of said pension fund.
Such bond shall be filed in the office of the city clerk of said city for the use of said board of trustees, or any person or persons injured by such breach.
40 ILCS 5/19-106