In the event that the Attorney General, any attorney for the Commonwealth, or the attorney for any county, city, or town investigates a complaint for a violation of § 59.1-527 and determines that the supplier has not violated the section, and if the supplier requests, the Attorney General, any attorney for the Commonwealth, or the attorney for any county, city, or town shall promptly issue a signed statement indicating that a violation of § 59.1-527 has not been found. Subject to the disclosures allowed by this section, it shall be the duty of the Attorney General, the attorney for the Commonwealth, or the attorney for any city, county or town, or their designees, that investigates any complaint for violation of § 59.1-527 to maintain the confidentiality of all evidence, testimony, documents, or other results of such investigations, including the names of the complainant, and the individual, corporation or other entity that is the subject of the investigation. Nothing herein contained shall be construed to prevent the presentation and disclosure of any such investigative evidence in an action or proceeding brought under this chapter.