I think I’ve finally figured out how they get a fedex tracking number that is from the U.S. on their fake checks.
I got a “business proposition” in my email a couple of weeks ago. It said basically I could work for this person by using a program like "Vistacheck" to create and print checks for them via Fedex. They would provide all the information (amount, bank, routing numbers, to address, etc). You just needed to do the printing and mailing.
I can't remember how they said I'd get "paid" for my service, but I remember thinking, "ahhh, that's how they do it". I think you were supposed to print a check out to yourself to pay for the service also.
So if you get a suspicious check, don't be thrown off by the fact it was possibly sent from the U.S. Most likely the check still originated in Nigeria. You can nearly always check the IP address on the email to find the real location of the sender.