29 C.F.R. § 70.25
(c) Unusual circumstances.
(1) Where the statutory time limits for processing a request cannot be met because of “unusual circumstances,” as set forth in the FOIA at 5 U.S.C. 552(a)(6)(B)(i)-(iii), and the component determines to extend the time limits on that basis, the component shall, before the expiration of the 20 working day deadline to respond, notify the requester in writing of the unusual circumstances and of the date by which processing of the request can be expected to be completed. If the component intends to extend the deadline to respond by more than ten working days, the component must:
(e) Expedited processing.
(1) Requests and appeals will be taken out of order and given expedited treatment whenever it is determined that they involve: