(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 employees immediate family, is threatened as a result of the employees assigned duties, the head of the agency concerned may approve appropriate subsistence payments for the employee or members of the employees family (or both) while occupying temporary living accommodations at or away from the employees designated post of duty.