D.C. Code § 21-111

When an infant residing outside the District of Columbia is entitled to property or to maintain an action in the District of Columbia, a general guardian or committee of his estate, appointed by a court of competent jurisdiction in the State or territory where the infant resides, or a person at the request of the guardian or committee, may petition the court for ancillary letters as guardian or committee. The petition shall be under oath, accompanied by certified copies of as much of the record and proceedings as shows the appointment of the guardian or committee and that he has given a sufficient bond to account for all property and money that may come into his hands by virtue of the authority conferred. The court may thereupon issue to the guardian or committee ancillary letters as such guardian or committee, without citation, or may cite such persons as it believes proper to show cause why the application should be refused; and the court shall require the security required by law in like cases from a resident guardian or committee.