During an investigation, the investigating officer may take appropriate action as follows:

(a) Issue complaint.

(b) Accept voluntary surrender of a credential or endorsement.

(c) Accept voluntary deposit of a credential or endorsement.

(d) Refer the case to others for further action. The investigating officer may refer the case to the Commandant or to an Officer in Charge, Marine Inspection, at any port for completion of administrative action if an adequate basis for action is found and the person under investigation and/or witnesses are not locally available.

(e) Give a written warning. The investigating officer may give a warning to any person holding a credential or endorsement. Refusal to accept the written warning will normally result in a withdrawal of the warning and the preferral of charges. An unrejected warning will become a part of the person's record.

(f) Close the case.