A year ago I was arrested for shoplifting in Illinois - it was the worst decision of my life and something that I will regret forever. I finally had the arrest expunged a month ago and now I am applying for jobs. I got my criminal file from the county and the arrest doesn't show [so everything was successfully expunged]. However, I am now applying to fortune 500 companies and am so scared that they will still find the arrest with extensive background checks or through third party firms.... even though I can legally say I was not arrested or convicted, should I just be honest and tell HR? How likely will they find it if I don't tell them ? I don't know what I should do...I am riddled with guilt and scared beyond belief. I would appreciate any advice, I have not slept for days ... this is going to haunt me forever.

People make bad choices. You made a bad choice. One bad choice does not necessarily have to haunt you forever. 

Full disclosure is always the best policy. Your record was expunged but you hit the nail right on the head when you mentioned third party firms. Background checks can be extensive and organizations do not rely on a sole source of information. Information is gathered from third party firms, employers, references, etc. If anyone but you knows about your shoplifting, HR is bound to find out about it too.

Bottom line for me as the average HR Manager, tell me about it. What did you do, how old where you, why did you do it, and what did you learn from it? Is your record clean otherwise? Can you honestly ensure me that it will never happen again? I can be much more open and willing to consider and weigh than if you attempt to hide. It goes to integrity and honesty. Shoplifting I can get past; dishonestly I cannot.

Good luck to you.