Possible Scenario in which Perp Used MH's Own Car.
Let's say that someone (not necessarily the driver, but just someone) somehow managed to obtain the keys to MH's car, and pick her up on the bridge that night.
If he broke her cell, took the battery & threw the cell & her open bag out the window of the car, we have to ask why she did not try to escape the car. He would have had to drive through city traffic with plenty of chances to get stopped at a light. In this case, he may have punched her very hard in the chin (maybe for the second time that night), and knocked her out cold.
Then, he headed westward on I64 towards Shenandoah State Park, which has many old disused roads, abandoned farms & infrastructure. (Fifty families were forced to leave their farms behind when the government decided to convert the area to wilderness park in the 1930s). Wanting to get rid of her body asap, he took no time to dig a shallow grave, but perhaps just threw her body down an abandoned well, mineshaft, tunnel or cave (perhaps not even bothering to kill her first).
Of course, this scenario would result in a lot of blood inside the car, which the perp later tried to remove. This blood could still be detected in the upholstery or rugs. Such evidence as her broken finger nail with his DNA on it might reveal the identity of the perp. Also, bits of soil may have certain minerals which could possibly indicate the most likely location where he left the car to dispose of the body.
Meanwhile, the Harringtons have taken a representative of some church group into their home, which might detract from overall objectivity of the investigation. What if some person who might reasonably be questioned is from a family that has a lot of political pull in the church?