The commission shall have the following functions, powers and duties:
No person shall be excused from attending and testifying or from producing books, records, correspondence, documents or other evidence in obedience to the subpoena of the commission, 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 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 so testifying shall not be exempt from prosecution and punishment for perjury committed in so testifying.
Mass. Gen. Laws ch. 151B, § 3