4 CFR § 28.49
Return of service
August 3, 2023
§ 28.49 Return of service.
When service of a subpoena is effected by a person other than a United States Marshal or Deputy Marshal, that person shall certify on the return of service that service was made either:
(a) In person,
(b) By registered or certified mail, or
(c) By delivery to a responsible person (named) at the residence or place of business (as appropriate) of the person to be served.