If an eavesdropping device is discovered, it should be reported to which of the following?

Reporting the discovery of an eavesdropping device to the State's Attorney of the county where it is found is the correct course of action due to the local jurisdiction's responsibility in handling violations of state law, including illegal eavesdropping activities. The State's Attorney is tasked with prosecuting criminal cases within their jurisdiction and is well-equipped to take any necessary legal actions regarding unauthorized surveillance.

While other entities, such as the Illinois State Police or the Attorney General, may be involved in broader investigations or enforcement activities, the local authority, represented by the State's Attorney, is more directly concerned with the specifics of the crime at the county level. The Federal Bureau of Investigation may handle federal crimes or cases involving interstate issues, but for state crime, particularly one like eavesdropping, local authorities have the primary responsibility to act.