Before initiating a civil action, the Office of the Attorney General shall conduct a preliminary investigation to determine whether there is reasonable cause to believe that any person committed a civil rights violation. During any examination, investigation, or hearing, the Office of the Attorney General may: subpoena witnesses; administer oaths; examine individuals under oath; and compel production of records, books, papers, contracts, and other documents. Unless obtained by a method independent of a subpoena, information obtained under a subpoena described under this section is not admissible in a later criminal proceeding against the person who provides the evidence. Except as provided in paragraph (2) of this subsection, the Attorney General may commence a civil action under this part. If the Attorney General obtains a conciliation or settlement agreement under this part, no action may be filed under this part with respect to the alleged conduct that forms the basis for the complaint covered by the agreement except for the purpose of enforcing the terms of the agreement. The Attorney General may intervene in a civil action concerning an alleged civil rights violation, if: the Attorney General certifies that the case is of general importance; and timely application is made.