Subpoenas may be issued by the Board to compel the attendance of witnesses at any investigation or hearing. The Board shall issue subpoenas at the request and on the behalf of the person complained against. (Amended 1969, No. 187 (Adj. Sess.), § 4; 1975, No. 249 (Adj. Sess.), § 2; 1983, No. 230 (Adj. Sess.), § 8a.)