Evidence in obedience to summons; immunity of witnesses

No person shall be excused from attending and testifying or from producing records, correspondence, documents or other evidence in obedience to the subpoena of the Attorney General, director, or hearing examiner on the ground that the testimony or evidence required of him may tend to incriminate him or subject him to a penalty or forfeiture, but no person 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. But he may nevertheless be prosecuted or subjected to penalty or forfeiture for any perjury or contempt committed in answering, or failing to answer, or in producing or failing to produce evidence in accordance with the subpoena, and any such testimony given or evidence produced shall be admissible against him in any proceeding concerning such perjury or contempt. The immunity herein provided shall extend only to natural persons so compelled to testify.