You searched for: “agent provocateur
agent provocateur (s); agents provocateurs, agent provocateurs (pl) (noun forms)
1. A person who is employed to encourage people to break the law so they can be arrested and prosecuted: "The government used agents provocateurs to try to undermine the opposition party so they would lose the election."
2. A secret agent implanted in an organization; such as, a trade union or political party, to incite its members to actions or declarations that will result in penalties or punishment.