A person shall not be excused from attending and testifying, or from producing documentary evidence, before the director in obedience to the subpoena of the director on the ground, or for the reason, that the testimony or evidence, documentary, or otherwise, which is required of him may tend to incriminate him or subject him to a penalty or forfeiture. A natural person shall not, however, be prosecuted or subjected to any penalty or forfeiture for, or on account of, any transaction, matter, or thing concerning which he may be so required to testify, or produce evidence, documentary or otherwise, before the director in obedience to a subpoena which is issued by him.
A natural person so testifying is not, however, exempt from prosecution and punishment for perjury committed in so testifying.