A United States district court, upon motion of the attorney for the Government, or its own motion, shall issue a protective order prohibiting harassment of a victim or witness in a Federal criminal case or investigation if the court, after a hearing, finds by a preponderance of the evidence that harassment of an identified victim or witness in a Federal criminal case or investigation exists or that such order is necessary to prevent and restrain an offense under
section 1512 of this title, other than an offense consisting of misleading conduct, or under
section 1513 of this title.