-that he deliberately sent her to her death while watching from the bridge?
I read a rather exhaustive book on the incident a number of years back. It had quite a few different possible scenarios and the reasons why they could have occurred.
One such possible scenario had him leaving the car after the local cop saw his car go by with only one person visible in it. Without it's lights on as I recall.
You can use your imagination about why she wasn't visible.
It had him exiting the area so he wouldn't be discovered with her. And she drove off the tiny bridge on the curve with no headlights on. A road he was familiar with, but she wasn't.
The next morning, drunk and stupid, he was informed of what happened and then began to scramble for a cover story with his advisers. Witnesses at the time were puzzled by his story because they were sure he was genuinely surprised about the accident initially.
I'm quite sure we will never know the truth and the fat ass old imbecile will take it to his grave with him.