EAST ST. LOUIS, Ill. – Investigators with the Illinois State Police have determined what caused the death of a central Illinois woman who was found dead near the Poplar Street Bridge on Tuesday morning.

According to an ISP spokesperson, officers from District 11 responded to the I-64/55 interchange for a single vehicle crash at approximately 4:08 a.m. in the westbound lanes of I-64.

One person, Makenze Coulter, was pronounced dead at the scene. She was 23.

Prior to the fatality, investigators said Coulter was riding in the front passenger of a 2017 Mercedes C300. A Bellefontaine, Missouri man was behind the wheel.

Coulter then stood up on the passenger seat and stuck her head and torso through the sunroof. She fell out of the sunroof as the driver was navigating a curve on the interstate and killed instantly.

State police shut down westbound I-64 for approximately four hours during the investigation. Cars were directed to the I-70 split.