PITTSBURGH — State authorities have ruled accidental the death of a mentally ill woman whose parents say she jumped out of their car on a highway, but a scientist who examined her remains for police disagrees with the official findings on what killed her.

A coroner concluded that Susan Bachman died from a skull fracture, and state police said the investigation was complete based on those autopsy results.

But Mercyhurst University professor Dennis Dirkmaat, who was hired by state police to examine the remains, said on Wednesday that the skull fracture happened after Bachman died, as her body decomposed. He agreed with state authorities, however, that there was no sign of foul play.

Bachman’s remains were found April 15 near where her parents say she ran into the woods last year after leaping from their car on Interstate 80 near Brookville, about 80 miles northeast of Pittsburgh. Her parents, Bill and Nancy Bachman of Julian, told police they were driving her to a mental health facility at the time.

Jefferson County coroner Bernard Snyder said that he was unaware of Dirkmaat’s findings when he issued his report and that the case now warrants additional study.

Dirkmaat said the fracture pattern “shows it didn’t relate to her death.”

“In this particular case we had a little hairline fracture but determined it was post-mortem,” he said.

State police have not commented on Dirkmaat’s conclusions. They had said earlier that the death was ruled accidental, based on autopsy results showing Bachman suffered trauma to her head as a result of her exiting a moving car.

Police found Bachman’s remains as they prepared to take a cadaver-sniffing dog to the heavily wooded area where her parents last saw her. Police prepared to search the area again because Bachman’s purse was found nearby in March. Her clothes had been found in another location nearby in September.

Snyder said he and Dirkmaat conducted separate examinations of Bachman’s partial remains: her skull and some of her vertebrae. Dirkmaat said it’s likely the rest of the remains were scattered or consumed by animals.

The coroner ruled April 30 that Bachman died from head trauma suffered from diving from the car based on the skull fracture he observed. Dirkmaat reported his findings, that the skull fracture happened after Bachman’s death, on May 26.