You can get the FBI report, FREEDOM OF INFORMATION.
You can get the FBI report anytime that is called FREEDOM OF INFORMATION. Go to the private finger printing place and ask him, What is the FREEDOM OF INFORMATION and How can I obtain my FBI report, I guess most of the finger printing guys knows about it.
Once you have taken your finger prints, send them to PHILLY by paying $15 or $20 fee and you will get your results in 3-5 weeks.
I have same problem, I got arrested by INS and have no convictions, They finger printed when arrested, It says on my FBI report,
Arrested : XYZ place on xx-xx-xxxx.
Convictions : NONE.
I did put it on my 485 as Arrested and explained what happend on a separate page.