Good point. With both people involved being dead, it is unlikely the police will put much pressure on her anyway. What would be the point?
I had a incident in 1996 in which I was under attack in a road rage situation. I fired at the person. His girlfriends statement of his actions/words during his attack is what got it dismissed as self defense. She was apparently pretty upset with her boyfriends actions and told the entire story. So who knows, she may tell the tale.