Hi allow me to jump in here as I JUST received my FBI background check with the apostille attached to it. I arrived in BA 3 months ago with all my paperwork even a background check that was apolstilled, however once I went to imigration they looked at my paperwork only to say, "problema." I wasn´t told that I needed a FBI background check. So I went to the local Police station in BA to have my fingerprints done then sent those with the application for a FBI background check to Washington. Once the background check was complete I had it sent to my assistant in the US and she had to send it to Virginia to have it apolstille in a different office. I finally received it today after a 2 1/2 month process. It is an attached form that has an embossed seal (you can hardly see it) and it looks like someone just printed it on thick manila color paper. If you need to start your job do what I did. I hired an attorney here for 1000 pesos and he helped me obtain a temporary work visa that ended up becoming a 2yr work visa due to an extension request that he put in. It´s now what you know but who you know that knows someone that knows someone else in BA. If you want the attorneys number I would be happy to ask my wife for his contact details and send it to you.
Sorry to be long winded.