Hello Jeanette: I'd encourage you to check out information about cougar sightings in Illinois at:
http://web.extension.illinois.edu/wildlife/directory_show.cfm?species=mountainlion
If you have general questions about cougars in Illinois, I can field some of your questions. The sighting near East Peoria is questionable from what I understand. But Joe Kath is the Endangered Species Manager with the Illinois Department of Natural Resources and he could provide you with an overview of sightings in Illinois, if not the specifics on that particular sighting. Many of the reports that come in end up being house cats or bobcats. Our goal is to educate people about cougars without stirring up unnecessary fear. If you wish to contact Joe he can be reached at: (217) 785-8764 or Joe.Kath@illinois.gov