Employment Law Questions? Ask an Employment Lawyer.
You should begin with HR. In the event that they refuse to assist you or you are not satisfied with their response you may be able to file a complaint with a State, local or federal agency depending upon what your are alleging. I would advise you to first contact HR, next review any relevant company policies regarding acceptable or ethical behavior in the workplace and finally follow up with the appropriate outside agency to find out if you have any further recourse outside of your employer's internal process.