As I said, I'm not sure the filmmakers got everything right, but it did seem to be quite well researched. You should check it out.. (It's an interesting movie in any case.) As I recall, in the film Patton's personal driver crashed into an Army truck that had been diverted into the opposite lane near a blocked intersection. Now the filmmakers could have just made all this up, but assuming that it corresponds even roughly with the facts, in order for the accident to be a murder, either:
1. Patton's driver would have had to be corrupted, or
2. The person diverting traffic would have had to know that Patton's vehicle was approaching, or
3. The occupants of the truck would have had to want Patton dead and be able to time his arrival at the intersection.
I'll let you do the background research. I imagine the books discussed in this thread all cover this incident.