Illinois Statutes Chapter 430. Public Safety § 66/35. Investigation of the applicant

(1) the National Instant Criminal Background Check System of the Federal Bureau of Investigation;

(2) all available state and local criminal history record information files, including records of juvenile adjudications;

(3) all available federal, state, and local records regarding wanted persons;

(4) all available federal, state, and local records of domestic violence restraining and protective orders;

(5) the files of the Department of Human Services relating to mental health and developmental disabilities; and

(6) all other available records of a federal, state, or local agency or other public entity in any jurisdiction likely to contain information relevant to whether the applicant is prohibited from purchasing, possessing, or carrying a firearm under federal, state, or local law.