Rule 3 Federal Rules of Criminal Procedure
Rule 3 of the Federal Rules of Criminal Procedure is about The Complaint. It is under Title II (Preliminary Proceedings) of the Rules.
The complaint is a written statement of the essential facts constituting the offense charged. Except as provided in Rule 4.1, it must be made under oath before a magistrate judge or, if none is reasonably available, before a state or local judicial officer.