A person is not excused from attending, testifying, or producing evidence before the Commissioner, in a proceeding brought by the Commissioner, or in obedience to a subpoena of the Commissioner on the ground that the testimony or evidence may: tend to incriminate the person; or subject the person to a penalty or forfeiture. If a person claims the privilege against self-incrimination as to a specific subject, and is then compelled to testify or produce evidence on that subject, the person may not be prosecuted or subjected to a penalty or forfeiture in connection with that subject. A person who testifies is not exempt from prosecution and punishment for perjury or contempt committed while testifying.