She petitioned a court in Chicago, Illinois in 1948 to change her last name, in order to make it sound more American. She immigrated about 10 years before the petition, as a child. I do have a copy of her naturalization certificate. I need to prove to the country where she was born that she is the same person that left that country. While I have her naturalization certificate for the USA, she changed her last name before marriage. Thus, I need to prove that she under her new name is the same person as her old last name. Her marriage certificate lists her maiden name as the one after the change. I tried to find who to contact in Illinois, however use to my lack of familiarity with the subject, I was not successful. Is there either a federal agency that would have such records, or a local court in Illinois that responds to such in questions? I don't know where in Illinois she petitioned.