During the struggle she might have managed to grab him. If he had a watch or bracelet on his left hand and had his left hand around her neck, in the struggle she might have cut his pinky with a bracelet or watch band that he wore.
Put your left or right hand on your own neck like you would strangle yourself. Notice that your pinky is forward and easiest to grab while your other fingers are close to the neck.
So, possibly the clue in registered picture has nothing to do with Chandra's ring but the ring he wore on his pinky was used to cover a scar ?
Just a wild thought.