Hi, My name is XXXXX XXXXX I’m happy to assist you with your question today. I’m sorry to hear about this employment matter. I understand you're essentially being harassed by way of an employee or employees filing multiple anonymous complaints against you.
An employer has a wide latitude, and in some instances (such as sexual harassment allegations) a legal mandate to investigate employee complaints. Your rights in this regard are very limited. That is to say, unless you believe the employer is doing these investigations for an illegal reason, which there are limited illegal reasons, then the employer can do these indefinitely. Such illegal reasons would be
the civil rights protections (e.g., age, race, sex, religion), violations of public policy (e.g., investigates for attending jury duty, for refusing to break the law, for reporting illegal activity by the employer (aka a "whistleblower violation"), or having some contractual right to a just cause employment (meaning the employer cannot investigate you without industrial due process - which basically insures a fair and accurate investigation and decision). Without any of these exceptions, courts find that the employer has a legitimate business right to operate its business however it sees fit and the court will not second-guess the employer's decision to investigate. These policies and decisions may in fact be awful and clearly not fair or even make good business sense. However, they are not ultimately unlawful.
The other way to attack this, is to determine who the anonymous employee is and individually issue a cease and desist and/or file a lawsuit against the employee. Unfortunately, Tennessee does not mandate employers provide employees with a copy of their employment file. A difficulty you'll have, as such, is that you'll have to file a lawsuit against a "john doe", then subpoena your employer, then issue the cease and desist against the employee.
The possible claims you'd have against him/her, personally, if s/he fabricated a misrepresentation of your character to your employer, which resulted in your harassment, would be the following: defamation per se, tortious interference with business relations, and intentional infliction of emotional distress. You'd have to be able to allege and prove that the person intentionally misrepresented facts to the employer, with the intention to defame your character and cause interference with your employment, and that it caused you financial and emotional distress as a result.
So, as you can see, this is a difficult situation for you as you'd have to file a lawsuit and subpoena your own employer to get to the bottom of it. Thus I wouldn't recommend it unless you felt you had no other option. The best option is to ask the employer to simply stop acknowledging these frivolous claims against you and/or take some employment action against the employee for abusing what is supposed to be a good faith system.
I believe this answers your question. However, if you need clarification or have follow-up questions regarding this matter, I will be happy to continue our conversation – simply reply to this answer. If you are otherwise satisfied with my response, please leave a positive rating as it is the only way I am able to get credit for my answers. Thank you, and I wish you all the best with this matter.