For a teacher residing in Korea to get an American FBI background check, said teacher simply submits a set of fingerprints to the FBI via airmail, and then waits several weeks to get a “no criminal record found” letter in the mail, which they then jump through hoops to have stamped and verified before handing it over to Korean immigration or the Ministry of Education before commencing their work contract.

What is the problem? Well, to start, nobody even checks to see WHOSE fingerprints you are sending to the FBI or relevant authorities in your home country. A criminal could very easily just submit someone else’s fingerprints and a false social security number, and come up with a “no criminal background found” letter. It’s just that easy. A wanted murderer can do it. A convicted pedophile can do it. Anyone can do it. In fact, take this into consideration: when an immigrant (or resident alien, or other non-citizen) commits a felony in the USA and thus obtains a documented criminal history, this person has NO American social security number under which their history is filed. The FBI relies ONLY on fingerprints to identify these people. Furthermore, the FBI’s criminal background checks are not intended to verify a person’s identity, but solely to verify the lack of a criminal history. The FBI’s website clearly states that the FBI CBC process conducted via mail IS NOT to be used for employment purposes, probably because the FBI has no capacity to verify that the prints sent to them anonymously in the mail belong to the person whose name is printed on the application form.

Source:  The Background Investigator
http://www.thebackgroundinvestigator.com/current_issue/index.asp?id=2359&title=The FBI