A person sworn and examined as a witness before either house, without procurement or contrivance, on his part, shall not be held to answer criminally, or be subject to any penalty or forfeiture for any fact or act touching which he is required to testify; nor shall any statement made, or book, document, or paper produced by any such witness be competent evidence in any criminal proceeding against such witness other than for perjury in delivering his evidence; nor shall such witness refuse to testify to any fact or to produce any book, document, or paper touching which he is examined, on the ground that he thereby will criminate himself, or that it will tend to disgrace him or render him infamous.