I don't believe I have come across this information if it does exist. I have often wondered that myself. I also wonder if maybe those were marks from some sort of pebble or something on the basement floor, or if she were taken somewhere else if the marks came from the other place. I think it is stretching it a bit if she were removed from the house and brought back, but as I have seen from other crimes (presented in documentaries, etc. on TV) that just about anything is possible these days.
I would think that if there were burn marks on her white shirt, this would have been noted somewhere and we probably would have heard of it by now, thus having no arguement about whether a stun gun was used or not. I would think that would be a definitive answer to that question.