(1) A member of the retirement board or an employee of the board may not:
(a) have an interest, directly or indirectly, in the gains or profits of any investment of money of the retirement system, except as provided in this section;
(b) directly or indirectly, for the member or employee or as an agent, in any manner use the money or deposits of the retirement system except to make current and necessary expenditures authorized by the retirement board; or
(c) become an endorser or surety or in any manner an obligor for money loaned by or borrowed from the retirement system.
(2) The assets of the retirement system may not be used for or diverted to any purpose other than for the exclusive benefit of the members and their beneficiaries and for paying the reasonable expenses of administering the retirement system.
(3) The board may not engage in a transaction prohibited by section 503(b) of the Internal Revenue Code.
(4) The assets of the retirement system must remain in trust until a warrant for the assets has been paid or an electronic funds transfer of system assets has been made in accordance with law.