>> reporter: this 127 page questionnaire is the first step towards gaining access to all three levels of security clearance. confidential, secret and top secret. it asks about your criminal and your employment history. it also asks whether or not you've ever illegally accessed a computer database and about your loyalty to the u.s. government. at higher levels, investigators may conduct background checks on close family members and examine records going back a decade. >> a lot will take a year or longer depending on the level. >> reporter: and may include former acquaintances and former coworkers. >> they will reach out to people you haven't thought of or people you forgot all about. >> reporter: for top secret clearance, some candidates will also undergo a psychological evaluation to assess trustworthiness. >> there are things you can see in somebody's past experience, whether they are more-or-less likely to be a whistle-blower