Fetching details from the dictionary...
accomplice; henchman
警察は共犯者を逮捕した。
The police arrested the accomplice.
共犯者が主犯の犯行を認めた。
The accomplice admitted to the mastermind's crime.
捜査の結果、ついに事件の共犯者が特定された。
As a result of the investigation, the accomplice in the case was finally identified.