(a) The investigating official, the reviewing official, and any employee or agent of the authority who takes part in investigating, preparing, or presenting a particular case may not, in such case or a factually related case:

1. (1) Participate in the hearing as the ALJ;
2. (2) Participate or advise in the review of the initial decision by the authority head; or
3. (3) Make the collection of penalties and assessment under 31 U.S.C. 3806.