An Illinois man was killed Friday night after his passenger vehicle went down a steep embankment and rolled, injuring a passenger near Dubois.

Charle Marquardt, 56, was not wearing his seat belt and was pronounced dead at the scene, according to a crash report from the Wyoming Highway Patrol.

Investigators say Marquardt was driving northwest on U.S. Forest Service Road 285 towards Double Cabin Campground at about 10:30 p.m. Friday. Near milepost five, the vehicle left the roadway in a slight left-hand curve.

The vehicle went down a steep embankment, hitting a road sign and rolling once, landing on its wheels. Marquardt was partially ejected from the vehicle.

The passenger suffered minor injuries and was taken to a hospital.

Alcohol use, driver fatigue and the driver's unfamiliarity with the road are all being investigated as contributing factors in the crash.

The road, which is naturally a mix of dirt and gravel, may have been muddy at the time of the crash, though weather conditions were reported to be clear.