Except as otherwise provided in this section, in the application of chapter 
84 of title 
5 to an employee of the Agency who is subject to such chapter and is designated by the Director under the criteria prescribed in section 
2013 of this title, such employee shall be treated for purposes of determining such employee’s retirement benefits and obligations under such chapter as if the employee were a law enforcement officer (as defined in section 
8401
(17) of title 
5).