Any municipal government with any sense at all carries a huge liability insurance policy, just in case of stupidities such as this one. I'd prosecute the he77 out of the guy anyway. Road rage is no joke. Physically, killing people is very easy, particularly at highway speed & a lot of people are packing heat these days as well. It's the moral & intellectual barriers that are difficult to overcome & the word "rage" covers that.
Locking her in a car in front of an oncoming train seems a bit harsh. Sort of like a really bad movie.
And just possibly, she was not actually guilty of a crime. We supposedly have courts, judges, and juries to sort out these things, along with "rules of evidence" and "due process". Well, it's a nice thought anyway.
That guy who locked her in the car should go to jail as a lesson to police officers: "Don't be -that guy-".