follow up

"criminal record certificate", do you mean the certificate from the country I used to stay in or the certificate from US.

If the FBI runs national criminal record check, then there shouldn't be any problem, cause I have a clean record in US. However I am afraid they have some international records and may track dowm overseas according to the recidency info from the petitioner.
I might be record in the country where I used to stay.
The thing is HOW far can they go or will they go?
You have no idea how regretful I am.