Answer:
a whistleblower
Step-by-step explanation:
Whistleblower is a term consisting of the individual who discloses to public authorities information concerning dishonest and illegal activities by another person or group. The way the whistleblower gets this information can be through illegal means, as seen in the question above, where Joe approves the use of GPS trackers to gather intelligence, despite having been told in the past that doing so without a warrant was a violation of suspects’ rights.
There are simple differences between a whistleblower and a person who makes a complaint. The latter can be any individual who knows about someone's responsibility for a crime that has been committed, revealing this information so that the proper authorities can do justice. On the other hand, the whistleblower is usually or has been involved in the crime, accusing others who also participated in it.