In the federal system, a person may be charged and arrested by way of a complaint or indictment. A complaint is a written statement of essential facts establishing the offense charged made under oath by the agent before a magistrate-judge. Based upon the complaint, an arrest warrant may be issued upon the establishment of probable cause to believe that an offense has been committed and that the defendant committed it. The warrant must list the defendant’s name, or description by which he can be identified, the offense charged, command that the defendant be brought without unnecessary delay before a magistrate-judge and be signed by the judge.
