A family that stopped to take in the view on Interstate 70 in Utah was in for a shock on Sunday, when they discovered an overturned semi truck, hidden out of sight from passing motorists at the bottom of a steep embankment.

After an initial investigation, the Utah Highway Patrol indicated that the driver had been dead “in excess of 24 hours.” He was not wearing a seat belt and was found partially ejected from the cab of the truck.

The driver has been identified as 46-year-old Deron J. Mason of Wiggins, Colorado.

According to Fox 13, the crash may have occurred during the early morning hours on Saturday, which would explain the lack of witnesses. The Utah Highway Patrol also stated that controlled substances are believed to be a factor.

A full investigation is currently underway in order to determine how, and when, the accident occurred.