This subchapter shall apply to any District employee or District retiree who is covered by the retirement program defined under § 1-702(7), or the retirement program established by §§ 1-626.03 to 1-626.12, or an officer, member, or retiree of the United States Park Police Force, or an officer, member or retiree of the United States Secret Service to whom the District of Columbia Policemen and Firemen’s Retirement and Disability Act (D.C. Code § 5-707 et seq.) applies.