No person shall be excused from attending or testifying, or from producing books, papers, correspondence, memoranda, and other records before the department, the board, or any referee or court, in obedience to any summons or subpoena, 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, except that such individual shall not be exempt from prosecution and punishment for perjury committed in so testifying.