((a)) Upon receiving the report of the prize master directed by , the United States attorney for the district shall promptly—
((1)) file a libel against the prize property;
((2)) obtain a warrant from the court directing the marshal to take custody of the prize property; and
((3)) proceed to obtain a condemnation of the property.
((b)) In connection with the condemnation proceedings the United States attorney shall insure that the prize commissioners—
((1)) take proper preparatory evidence; and
((2)) take depositions de bene esse of the prize crew and of other transient persons who know any facts bearing on condemnation.