A woman was shocked to discover part of an elderly man's face while taking her car through a car wah.

Veterinarian Kimberley Kreige found the face fragment while visiting Super Car Wash, in Livingston, Montana.

The remains belonged to Elgie Bedford, aged 81, who had been killed hours earlier in a hit-and-run accident on a rural road a few miles away while on his way to see grandchildren.

Mr Bedford had been run over by truck driver David Welk, who fled the scene immediately after the accident.

Another driver, Wyran Young, unwittingly ran over Mr Bedford's body some time after the fatal collision - leaving the victim's face attached to her car.

Young took her vehicle to the car wash later that day, at which point the Mr Bedford's face ended up on the floor.

Ms Kreig later came across the body part and immediately reported it to police - who she claimed “treated (her) as a criminal suspect” by having her car impounded, demanding a blood sample and holding her for several hours.

She says she had been left badly tramautised by the incident two years ago and needed counselling as a result.

Ms Kreig claims Welk, who has been convicted of driving over and killing Mr Bedford, should have immediately notified authorities, Courthouse News reports.

She is now suing Welk's former employer, CRST Expedited, for medical expenses, lost income, negligence and emotional distress.

She said Welk should have called the police instead of leaving “the body on the highway, knowing that someone could be held responsible for the hit-and-run death.”

Young, 31, maintained she thought she had hit a pile of clothing and not a dead body - and all charges against her were dropped.