In the early hours of June 29, 1967, Mansfield was traveling on a dark stretch of U.S. Route 90 near Slidell, Louisiana. She was riding in the front passenger seat of a 1966 Buick Electra, accompanied by her lawyer and companion, Samuel S. Brody, and the driver, Ronald B. Harrison. In the back seat were three of her children: Miklós, Zoltán, and Mariska Hargitay.

Multiple deep lacerations on her hands and lower extremities. Status at Scene

At approximately 2:25 a.m., the vehicle approached a stretch of highway shrouded in a thick cloud of white insecticide emitted by a nearby mosquito-fogging truck. The semi-truck directly ahead of the Buick slowed down drastically due to the lack of visibility. Harrison, blinded by the chemical fog, failed to see the trailer in time. The Buick crashed at high speed into the rear of the tractor-trailer, sliding directly underneath the heavy trailer bed. The impact sheared off the entire roof of the car down to the window line. How Seatbelts Save Lives: Lessons From Celebrity Tragedies

The autopsy findings—reported by Dr. Chetta and often discussed by the forensic experts of the time—show that while the injuries were gruesome, the head and body remained connected. Official Cause of Death:

The official autopsy report for Jayne Mansfield provides a clinical breakdown of the injuries that led to her death. Contrary to the widespread rumor that she was decapitated, the report clarifies the actual nature of her fatal trauma.

At approximately 2:25 AM, on a dark stretch of U.S. Highway 90 near Slidell, Louisiana, the Buick crashed at high speed into the rear of a tractor-trailer. The truck had slowed down behind a city vehicle that was spraying a thick fog of mosquito insecticide, which severely obscured visibility on the road. The Buick slid directly underneath the rear of the trailer, shearing off the top of the car. All three adult passengers in the front seat were killed instantly. Remarkably, the three children sleeping in the back survived with only minor injuries. Decapitation vs. Craniocerebral Trauma

The tragedy of Jayne Mansfield's death led to significant improvements in automotive safety. The car had driven under the rear of the tractor-trailer, which directly caused the catastrophic roof damage. This specific type of crash prompted the implementation of "Mansfield bars" or "DOT bumpers"—the heavy steel bars that hang from the rear of tractor-trailers to prevent cars from sliding under them.