I'd contact the Fulton County Clerk & Recorder of Deeds, www.fultonco.org/officials/elected/county-clerk/vital-record...
and ask if they have death records that early.
The Illinois Regional Archives Depository, https://www.cyberdriveillinois.com/departments/archives/IRAD...
doesn't have death records that early.
I'd contact the Fulton County Historical and Genealogical Society, www.rootsweb.ancestry.com/~ilfchgs/
and ask if they have a local death index, indexed newspaper death notices and cemetery records. Successful Searching!