5 U.S.C. § 5706a

(a) Under regulations prescribed pursuant to section 5707 of this title , when the life of an employee who serves in a law enforcement, investigative, or similar capacity, or members of such employee’s immediate family, is threatened as a result of the employee’s assigned duties, the head of the agency concerned may approve appropriate subsistence payments for the employee or members of the employee’s family (or both) while occupying temporary living accommodations at or away from the employee’s designated post of duty. (b) When a situation described in subsection (a) of this section requires the employee or members of the employee’s family (or both) to be temporarily relocated away from the employee’s designated post of duty, the head of the agency concerned may approve transportation expenses to and from such alternate location.