The court may order the defendant or the state or both to show cause why expert witnesses should not be appointed, and may request the parties to submit nominations. The court may appoint any expert witnesses agreed upon by the parties, and may appoint witnesses of its own selection. An expert witness shall not be appointed by the court unless the witness consents to act. A witness so appointed shall be informed of the witness’ duties by the court in writing, a copy of which shall be filed with the clerk, or at a conference in which the parties shall have opportunity to participate. A witness so appointed shall advise the parties of the witness’ findings, if any, and may thereafter be called to testify by the court or by any party. The witness shall be subject to cross-examination by each party. The court may, unless otherwise provided for by rule, determine the reasonable compensation of such witness and direct its payment out of such funds as may be provided by law. The parties also may call expert witnesses of their own selection.