Upon the acquittal, dismissal of charges, nolle prosequi, or any other final disposition concluding the innocence of any trustee, advisory committee member, officer, or employee of the Retirement System brought before any regulatory body, summoned before any grand jury, investigated by any law-enforcement agency, arrested, indicted, or otherwise prosecuted on any criminal charge arising out of any act committed in the discharge of his official duties which alleges a violation of state or federal securities laws, the Board may reimburse all or part of the cost of employing legal counsel and such other costs as are demonstrated to have been reasonably necessary for his defense. The Board shall provide for the payment of such legal fees and expenses out of funds appropriated for the administration of the Retirement System.