The parents of a missing Illinois teen hope for more clues in the disappearance of their son after Wisconsin authorities found his blankets and a backpack near the area where his car was found.

The Sauk County Sheriff's Office will search the area along the Baraboo River Tuesday.

Lee Cutler, 18, of Buffalo Grove, Ill., went to a birthday party Friday night and stayed over at a friend's house. Cutler's 2007 Toyota Corolla was found parked at a rest stop after he was reported missing two days earlier.

Beth and Barry Frazin, Cutler's parents, traveled to Sauk County, Wis., from their suburban Chicago home as soon as they learned the car was found.

Cutler's cell phone indicated the last time it was used was at 12:30 am. Saturday.

Barry Frazin said authorities planned to conduct a dive search in the Baraboo River Tuesday as a precautionary measure.

The Associated Press contributed to this report.