BISMARCK, Ill. (AP) _ Federal investigators on Tuesday examined the wreckage of a small plane that crashed in an eastern Illinois cornfield, killing four people.

The plane crashed shortly before 5 p.m. Monday in this community on the Illinois-Indiana border about 85 miles northwest of Indianapolis.

Vermilion County Coroner Peggy Johnson identified the victims as pilot Dennis M. Kriewaldt, 50, of Watertown, Wis.; his wife, Jeanette, 47; his son, Adam, 26; and Adam's fiancee, Jacqueline Theder, 25, also of Watertown.

They were returning from a visit to Florida and had planned a refueling stop at Vermilion County Airport, five miles south of the crash site along Illinois Route 119.

National Transportation Safety Board officials were looking into factors such as weather or the pilot's decisions, Johnson said. The sky was slightly cloudy at the time of the crash, but there was no rain.

``They say it will be six months before they have any definitive answers,'' Johnson said.