How can I figure out who ran a background check on me?

Here is the deal, my employer ran a background check on me without my written consent. I found out they did this, but I need proof they did. Does anyone know how I can get proof of who ran a background check on me?How can I figure out who ran a background check on me?
Most are ran at the local police station. or Identex. These are a couple, but there are many places. You can ask for a copy of your employment file under the Right to Know Act. That may give you an indication of who did it as it may be written in your files. Under the Right to Know Act you can demand it.How can I figure out who ran a background check on me?
How do you know? If you know, then there is your proof...just show the police or your lawyer, how tyou know they did it and its a done deal.