A provocateur has the job of convincing people to commit crimes. Usually, a provocateur works for a police department or government.
If police want to catch a criminal in the act, they might use a provocateur to induce the suspect to buy drugs, for example, so officers can swoop in and make an arrest. Provocateur is a shortened form of "agent provocateur," used since the late 1800s to mean "person hired to make trouble." When police officers pretend to join protests — such as those at political conventions — with the goal of inciting people to violence and then arresting them, they act as provocateurs.