My question involves labor and employment law for the state of: Colorado

A month ago a recruiter from a large telecommunications company contacted me regarding a job. I am a felon and currently on parole. They had found my resume through monster.com. After 3 phone interviews and an in person interview I was offered the job pending a background check. I was set to start 10/10/08 but my background check did not get finished by then so they changed my start date to 10/17. Last thursday I spoke with the recruiter who originally contacted me and asked was i cleared to start. He said he thought so but was not sure. He said he would check and get back to me. He called me back within 10 mins and stated "Your greenlighted so you should go ahead and quit your job. You are starting on monday." I went ahead and quit my job at that point since he said I was clear. The next morning I received a voicemail from his supervisor, the person who oversees the whole hiring process. His voicemail said Congrats, Your cleared to start on monday. I saved this voicemail. I started work this week and then on my 3rd day they pulled me out and walked me out since they claimed they didn't know. I clearly stated I was a felon on my background check application. There was a 3 year gap in employment on my resume. I know they are in violation on discrimination here since they "cleared" me. What do I do? How do I take action against this company?