I believe ours are basic criminal background checks run through our state's Department of Public Safety. I don't know for sure, but I'd bet they are only state level criminal checks, PERHAPS with a national sex offender search.
We just found out that the background checks our school has been using for volunteers is not very reliable. For one thing, they do not verify the information that is turned in; if someone was to fill out a form with nothing but made-up information, it would probably come back "cleared." As long as the information on the form does not match up with an arrest record in the computer, then the check comes back indicating there is no arrest record for this person (they don't verify that the person actually exists!). We also found out that they don't check arrest records beyond our state. With one school in the district currently dealing with its name in the news after having its PTO President arrested last month for stealing PTO money, we need to find a background check that is more thorough and reliable. Any suggestions?