arrest record with Secret Service

I was arrested and held by Secret Service at an international political event in San Francisco, 1981. The National Lawyers Guild represented me and the four other women involved in the action, pro bono. (We were temporarily jailed by San Francisco police, released OR, appeared at court and paid a small fine.) The arrest document noted that copies should be forwarded to Secret Service. This took place when computerization was in its infancy, so I don’t know if the records still exist or are accessible. With the current political climate, I want to know what records regarding my arrest are held by Secret Service or other agencies. I have been asked to submit letters of support for an immigrant seeking to extend her stay legally in the U.S. (she has U.S.-born children and a husband here) and the letter is supposed to go to Homeland Security, with a copy of my birth certificate. I am wary about whether my old arrest record might be used against this immigrant. I am also wary about putting myself under Homeland Security scrutiny. I need help to obtain the arrest record but I also don’t want the request itself to cause trouble. Thank you for any pointers.