Care should be taken that the Marshal of the district is promptly informed by the United States Attorney of the dismissal of a complaint, whether by the court or a judicial officer, in order to facilitate cancellations of unexecuted arrest warrants as provided in Fed. R. Crim. P. 4(d)(4). Such notification is also important when a warrant of arrest is outstanding in connection with a detainer lodged against a defendant who is confined in another district. Since the warrant will have been forwarded by the Marshal of the district where it was issued to the Marshal in the district of detention, the warrant will have to be returned to the Marshal of the issuing district for cancellation by the judicial officer after the complaint has been dismissed.