Updated: 12/06/10 4:55 p.m.

(WBBM/CBS) – A car crashed in the middle of the night. One person was found dead. But another disappeared.

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A mother of four is missing. The only trace police have of Tanya Shannon are footprints in the snow that lead away from a deadly car crash that killed her husband.

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It happened near Seneca. Dale and Tanya Shannon were heading home to Ransom, Ill. from a holiday party at the Knights of Columbus in Streator, which is about a 30-minute drive.

Tanya was wearing a bright red ball gown.

As they drove home on a snowy stretch of road in rural Brookfield Township, their car spun out of control, hitting a pole.

They were a few miles from their home, and it was 1:45 a.m. Sunday.

A LaSalle County Sheriff’s deputy on patrol came upon a one-car crash.

Dale Shannon, 41, of Ransom, Illinois, was dead in the driver’s seat. Authorities say he was killed instantly.

Footsteps leading from the roadway indicate Tanya survived, but since early Sunday morning, she has not been seen.

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Authorities found Tanya’s formal shoes in the car and one slipper in the mounding snow.

The effort to locate any trace of Tanya has been going almost nonstop since early Sunday morning. Search crews have been braving arctic wind chills to find some evidence of where she may be. There have been air searches, crews on snowmobiles, but so far, no sign of the mother of four.

“For some unknown reason, she hasn’t contacted her family. She has four children. We understand she’s a very loving mother,” said LaSalle County Sheriff Tom Templeton.

But Templeton worries that because of “injuries that were serious enough to have killed her husband at the scene of the crash, did she also suffer injuries that were so serious that caused her to fall into a ditch?”

Tanya Shannon is 40 years old, 5 feet, 2 inches tall, 125 pounds, with shoulder length strawberry blond hair and green eyes.

She was last seen wearing a red dress and a gray fleece jacket with a hood.

Her family believes she must have been injured, and perhaps disoriented, and was picked up by somebody and taken someplace for treatment.

“Maybe [another person] took her to a hospital … or something of that nature,” said her sister-in-law, Donna Baker, who is now caring for the couple’s four children.

Search efforts were called off Monday night and coordinators are unsure if they will resume Tuesday.

No one matching Tanya’s discription has surfaced in any area hospitals.

So the mystery goes on: did someone pick her up along the roadway? Is she somewhere dazed and confused? Questions her family is asking while they also make funeral arrangements for her husband.

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CBS 2’s Vince Gerasole and Newsradio 780’s Mike Krauser contributed to this report.