45 C.F.R. § 1149.74
These procedures separate the functions of the investigating official, reviewing official, and the ALJ, each of whom report to a separate organizational authority. Except for purposes of settlement, or as a witness or a representative in public proceedings, no investigating official, reviewing official, or NEA employee or agent who helps investigate, prepare, or present a case may (in such case, or a factually related case) participate in the initial decision or the review of the initial decision by the authority head. This separation of functions and organization is designed to assure the independence and impartiality of each government official during every stage of the proceeding. The representative for the NEA may be employed in the offices of either the investigating official or the reviewing official.
45 C.F.R. § 1149.74