A criminal complaint charges the person named or an unknown person with a particular offense. For example, after the bombing of a federal building in Oklahoma City in 1995, authorities issued a JOHN DOE complaint, charging an unknown person or persons with the crime.
A criminal complaint must state the facts that constitute the offense and must be supported by PROBABLE CAUSE. It may be initiated by the victim, a police officer, the district attorney, or another interested party. After the complaint is filed, it is presented to a magistrate, who reviews it to determine whether sufficient cause exists to issue an arrest warrant. If the magistrate determines that the complaint does not state sufficient probable cause, the complaint is rejected and a warrant is not issued. In federal court, the complaint is presented under oath (Fed. R. Crim. P. 3).