The commissioner of management and budget shall be ex officio treasurer of the retirement funds of the association and the general bond of the commissioner of management and budget to the state must be so conditioned as to cover all liability for acts as treasurer of these funds. All money of the association received by the commissioner of management and budget must be set aside in the state treasury to the credit of the proper fund or account. The commissioner of management and budget shall transmit monthly to the executive director a detailed statement of all amounts so received and credited to the funds. Payments out of the funds may only be made as payments issued by the commissioner of management and budget, upon abstracts signed by the executive director; provided that abstracts for investment may be signed by the executive director of the State Board of Investment.