I want to know if I can sue my employer for slander.

An anonymous letter was recently sent to the State Auditor with regard to hostile work environment, financial issues and such. After a very brief and undocumented investigation, it was decided that there were no issues. In the meantime, my employer, who is obessed with finding out who wrote this so called letter, has contacted individuals commenting that I was the one responsible. I am also being discussed as the "anonymous letter writer, at functions because of my employer'scomments. These comments are being made to individuals that I have worked very hard to gain their trust and validate my reputation as being morally and ethically sound. Then most recently, I discovered that not only was my employer making these sladerous comments, but so are individuals in our finance department.