In any investigation or hearing by the Commission, a person may not be excused from testifying or producing a document in accordance with an order of the Commission or its secretary on the ground that the testimony or document may: tend to incriminate the person; or subject the person to a forfeiture or penalty. Except as provided in subsection (c) of this section, a person may not be prosecuted, punished, or subjected to any forfeiture or penalty because of any act, transaction, matter, or thing about which the person testifies under oath or produces a document, on order of the Commission or an examiner or inspector of the Commission. A person who commits perjury is subject to prosecution or punishment.