The department of developmental disabilities may appoint and commission any competent agency or person, to serve without compensation, as a special agent, investigator, or representative to perform a designated duty for and in behalf of the department. Specific credentials shall be given by the department to each person so designated, and each credential shall state the:
(A) Name;
(B) Agency with which such person is connected;
(C) Purpose of appointment;
(D) Date of expiration of appointment;
(E) Such information as the department considers proper.