An authorized third-year law student or staff instructor, when under the supervision of a circuit public defender, may assist in criminal proceedings within this state as if admitted and licensed to practice law in this state except that all pleadings and other entries of record must be signed by a circuit public defender or by his or her duly appointed assistant and that, in the conduct of a trial or other criminal proceeding, a circuit public defender or his or her duly appointed assistant must be physically present.