A perpetrator is a person who committed a crime.
In the instance of a joint crime (if more than 2 persons are involved in a crime) it is necessary to clarify the criminal liability and punishment among the defendants. The individual who did commit the crime is named as the “first-degree principal” according to the 18 U.S. Code §2; the person who did not commit the crime directly, but did offer any assistance to the perpetrator, is defined as the “second-degree principal” or “accessory”. There are two kinds of accessories, the “accessory before-the-fact” and the “accessory after-the-fact”. It is a clear rule that the punishment of an accessory after-the-fact shall not be more than one-half of the principal, according to the 18 U.S. Code §3.
[Last updated in May of 2022 by the Wex Definitions Team]