31 C.F.R. § 16.4 – Investigation.

(a) If an investigating official concludes that a subpoena pursuant to the authority conferred by 31 U.S.C. 3804(a) is warranted—
1. (1) The subpoena so issued shall notify the person to whom it is addressed of the authority under which the subpoena is issued and shall identify the information, records, or documents sought;
2. (2) The investigating official may designate a person to act on his behalf to receive the information, records, or documents sought; and
3. (3) The person receiving such subpoena shall be required to tender to the investigating official or to the person designated to receive the information, records, or documents, a certification that the information, records, or documents sought have been produced, or that such information, records, or documents are not available and the reasons therefor, or that such information, records, or documents, suitably identified, have been withheld based upon the assertion of an identified legal privilege.
(b) If the investigating official concludes that an action under the Program Fraud Civil Remedies Act may be warranted, the investigating official shall report the findings and conclusions of such investigation to the reviewing official.
(c) Nothing in this section shall preclude or limit the investigating official's discretion to refer allegations directly to the Department of Justice for suit under the False Claims Act, 31 U.S.C. 3729-3731, or for other civil relief, or to preclude or limit such official's discretion to defer or postpone a report or referral to avoid interference with an investigation into criminal misconduct or a criminal prosecution.
(d) Nothing in this section modifies any responsibility of the investigating official to report violations of criminal law to the Attorney General.