how does USCIS find out that you overstayed?
 

Let's say I entered the US legally circa 2001, had someone return my I-94 on time, did high school and college in here, still speak Spanish like a native speaker, go back to Mexico and obtain a master's degree and work experience in my field, work for a few years over there and later decide to come back as a tourist. What are the chances of them finding out that I lived in the US for a little over a decade, how far back do they review your life? I remember the process to obtain a tourist visa; they basically required paycheck stubs, sometimes testimony from friends and relatives, proof of residency of your country of origin, and utility bills.