principal offender; principal offense
Legal term for the main perpetrator or the primary crime itself. In news contexts, often refers to the ringleader or main culprit.
The police arrested the principal offender.
The principal offender in this case has not yet been identified.
The principal offender in that robbery case is still on the run.
He was arrested as the principal offender in that fraud case.
首謀者 emphasizes the person who planned or instigated a crime or plot, whereas 主犯 is the legal term for the main offender who actually committed it.
主犯 is a legal term for the principal offender in a crime, while 元凶 is broader and can describe any ringleader or root cause, legal or not.
主犯 is the principal offender who leads a crime, while 共犯 is an accomplice who assists but is not the main perpetrator.
Compound of 主 (main, principal) and 犯 (crime, offense). The reading is on'yomi.