Except as herein provided, no member of the board or of the retirement board, nor any member of the retirement system or employee of the district, shall have any interest direct or indirect in the making of any investment or in the gains or profits accruing therefrom, and no such person, directly or indirectly, for himself or as an agent or partner of others, shall borrow any of its funds, nor shall any such person in any manner use the same except to make such current and necessary payments as are authorized by the retirement board, nor shall such a person become an endorser or surety as to, or in any manner an obligor for investments of the retirement
fund.