means The person who actually committed a crime, offense, or wrongdoing — the doer of the deed.

from From Latin perpetrare, 'to carry through, accomplish, perform,' built from per- ('thoroughly') and patrare ('to bring about, complete'). Oddly, in classical Latin it could mean accomplishing anything at all — good or bad. But by the time it reached legal English (via the noun perpetrator), it had specialized darkly: you no longer 'perpetrate' a kindness, only a crime, a fraud, or a hoax. The word kept its formal Latin posture while quietly committing itself entirely to wrongdoing.