No person shall be excused from attending and testifying or from producing books, papers, correspondence, memoranda, and other records before the Commission, the Board of Review, the chairman of an appeal tribunal, or any duly-authorized representative of any of them, or in obedience to the subpoena of any of them in any cause or proceeding before the Commission, the Board of Review, or an appeal tribunal, on the ground that the testimony or evidence, documentary or otherwise, required of him may tend to incriminate him or subject him to a penalty or forfeiture; but no individual shall be prosecuted or subjected to any penalty or forfeiture for or on account of any transaction, matter, or thing concerning which he is compelled, after having claimed his privilege against self-incrimination, to testify or produce evidence, documentary or otherwise, except that such individual so testifying shall not be exempt from prosecution and punishment for perjury committed in so testifying.