public service murder
n.— «The former dean of the Brooklyn Law School sounded like an overworked detective who speaks of “public service murders” bad guys killing bad guys.» —“Bad Judgment On Mafia Big” by Mark Kriegel N.Y. Daily News Apr. 15, 1998. (source: Double-Tongued Dictionary)
Further reading
When a teenager went a week without talking as part of a school project, he noticed a surprising side effect: Instead of rehearsing a response to what other people were saying to him, he was focused on listening — and feeling smarter as a result...
Susie Dent’s murder mystery Guilty by Definition (Bookshop|Amazon) follows a lexicographer in Oxford who becomes a sleuth of a different kind, seeking the culprit in a long-unsolved killing. A lexicographer herself, Dent includes lots of obscure and...