per ‧ pe ‧ tra ‧ tor /ˈpɜːpətreɪtə, ˈpɜːpɪtreɪtə $ ˈpɜːrpətreɪtər/ BrE AmE noun [countable] formal
someone who does something morally wrong or illegal ⇨ culprit :
The perpetrators were never caught.
perpetrator of
The perpetrators of racially motivated violence must be punished.