A road crew cutting grass found the suitcases early Thursday afternoon and simply moved them aside, police said. A passerby spotted them a short time later and called police.
In a news release, Geneva Police Chief Steven R. Hurley called the grisly discovery "an isolated incident." He said the two people were not killed in the area where their bodies were found.
Detectives are going through missing persons reports in an effort to identify the bodies, Hurley said. Autopsies were to be conducted Friday.
Geneva is a small town in a rural area about 80 miles northwest of Chicago and 40 miles southwest of Milwaukee.