Naturalization and immigration papers can be obtained from the Peoria CountyClerk's office Archives Department 324 Main Street Peoria, Il61604 Phone 309-672-6064
You can call to see if your relative is on the index. They will tell you how many pages and the cost of the documents. You have to send cash or money order first. The lady's name in the ARchives Dept. is Angie. Hope this helps.