Can the USCIS find out that I worked illegally?

Karen writes, "I am one of those undocumented immigrants who did not think it through and have worked for years using a fake Social Security number.  What is the probability that the USCIS can find out if I did so?"

Assume that all crimes will be caught:  With all the cool technology out there, if the Government wants, it can find out almost anything.  With more than ten million immigrants in the country and many of them working like you for years, living comfortably, buying homes, it might seem that no one cares, but the reality is that when applying for an immigration benefit, you are voluntarily subjecting yourself to scrutiny by the agencies.  While you have not really explained the complete details of your case because a lot depends on what type of a paper trail exists for you and what exactly you did and how, but it is fair to say that if you broke the law you should be aware that you maybe caught (the fact that you may have heard of people who even became citizens despite breaking the law is no guarantee that everyone else can expect the same result -- there are lots of people who are deported each year or denied immigration benefits because of being a lawbreaker or lying about something).

An attorney can help you better understand your risks:  Only a consultation with an attorney during which you go over everything with him can determine your risks.  No one really knows at this point to what extent USCIS will dig into each application, but from what I understand lying is a terrible idea (in other words, if you did so, you should not lie about it because you assume that you will not be caught like many other) and I always like to work with the hypothesis that at some point it will come up regardless of how hard you tried to hide it (many people do not realize that even when you get paid under the table or from the employer's personal checking account, the paper trail is long and easy to track down). 

If you receive a notice to appear in person for an interview or a request for evidence (RFE), you will be all by yourself in front of a very competent officer who will have a huge dossier on you (and you would not know what information is in there) and at that point lying can put you in all kinds of legal problems, including immediate arrest and deportation.  I can simply point out the scenarios, but please, I advise you to get all your facts together and schedule an interview with a competent attorney who genuinely wants to help you rather than is interested in just filing your application (which is exactly what a lot of attorneys are trying to do these days).  Remember that in picking an attorney keep in mind your own long term interest and how something small now can come to bite you down the road.  That is why do not seek free consultation for this application.  Instead, pay separately for a consultation on whether to apply or not so that you can get unbiased advice.