BOONVILLE, Mo. (AP) — Authorities have determined that a South Dakota driver who was found dead after a crash on Interstate 70 in central Missouri was fatally shot.

The Missouri State Highway Patrol announced Wednesday the cause of death for 40-year-old Melissa Peskey, of Sioux Falls, South Dakota.

The patrol says Peskey was found dead in the driver’s seat at 10:30 p.m. on Dec. 23 in Missouri’s Cooper County. An autopsy was conducted this week. The patrol says it indicates that she was killed by a weapon that was fired outside her vehicle.

The patrol says the investigation is ongoing. The release didn’t say whether anyone had been arrested, and a patrol spokesman didn’t immediately return a phone message seeking comment.