Shill and Whistle-blower

Shill noun - A decoy who acts as an enthusiastic customer in order to stimulate the participation of others.

Whistle-blower and shill are semantically related in informer to police topic. In some cases you can use "Whistle-blower" instead a noun "Shill".

Whistle-blower noun - A person who provides information about another's wrongdoing.

Shill and whistle-blower are semantically related in informer to police topic. Sometimes you can use "Shill" instead a noun phrase "Whistle-blower".