Whenever a petition is filed with the Public Officer by a public authority, as defined in N.J.S.A. 40:48-2.4, or by at least five residents of the Borough, charging that any building is unfit for human habitation or occupancy or use, or whenever it appears to the Public Officer, on his own motion, that any building is unfit for human habitation or occupancy or use, the Public Officer shall, after a preliminary investigation discloses a basis for such charges, issue and cause to be served upon the owner of and parties in interest in such building a complaint stating the charges in that respect and containing a notice that a hearing will be held before the Public Officer (or his designated agent) at a place therein fixed not less than 10 days nor more than 30 days after the serving of said complaint, and that the owner and parties in interest shall be given the right to file an answer to the complaint and to appear in person or otherwise and give testimony at the place and time fixed in the complaint, and that the rules of evidence prevailing in the courts of the State of New Jersey shall not be controlling in hearings before the Public Officer.