I do want to add a few things here in terms of perspective....and fwiw I became completely fascinated by the Borden murders because I grew up not far from where they were committed and my dad had a number of books regarding the case. I would sneak them when I was a teen
First of all, this was not a warm and fuzzy family. These were stoic New Englanders not really given to much in the way of either affection or hysteria. Lizzie may very well have looked calm but have been about to drop from the events of the day, hence Alice's insistence on staying and the Dr's application of laudanum to help her sleep.
They were also penny pincher's to the nth degree-I am completely unsurprised to read that Lizzie had the old sofa recovered and continued to use it. This was a family that ate leftovers regardless of their age and kept scraps of everthing in the event they could be reused....lead for sinkers, broken axes etc.
Given that Abby was facing her killer, I have to believe that Lizzie walking into the room with an axe, either covered with a slicker or naked (depending on your favorite version) would have caused her to react. So who ever approached Abby was someone who did NOT cause her to react much even though they were carrying an axe...which is why my vote is Bridget.
But I think that Lizzie had an idea of what was going on in the house that day....or certainly what had happened. Only because we know she wasnt in the barn (the dust was undisturbed) and it was hot as Hades that day...
I do not think either Borden girl was heartbroken at the death of their parents. I think they were relieved. I think that Lizzie was at a minimum asexual-I mean who would not be put off of men after living with one such as Andrew? He was not a nice guy, although I dont know if I buy the incest theory. He loved Lizzie to a degree, I think. This was an extremely rigid and oppressed family-and I think the Uncle had more than a little bit of knowledge himself. JMO.
I really think that there were a lot of factors that contributed to the family dynamic that was "poisoning" to Lizzie's character. I think the fact that her father cut off the gas to the house and made them use oil lamps, sold the horse and carriage, and to me...seemed to dominate the women in the house totally and utterly, I really think this caused Lizzie to repress a lot of feelings.
I am a medium, as in yes, I see dead people, can pick up on energies and the like. I went to the house not long ago...and while I can't back up my theory with actual evidence, I can tell you my impressions of the house. I didn't pick up much actually related to the muder surprisingly enough. The feeling that overwhelmed me, that made me sick to my stomach and gave me a headach was OPRESSION. Total oppression. I did NOT expect that when I got there. I thought the murders/death would "slap" me in the face but they didn't, it was the opression of Andrew/the father. You know when you walk into a room after 2 people have had an arguement and the air feels all thick and even if the people are not talking, you can tell that they had been arguing? That's what the house felt like to me, except it was so much stonger.
I just "feel" that there was more to the Andrew domination of the family than just words. I just have this gut feeling that at some point one, if not both of the girls had been molested in some way or abused. I think in such a society where "marrying" girls were ones that were "pure" that possibly this is why neither Lizzie or Emma ever married. Sort of like they were "tainted". I think this gives great weight to your comment about them being "asexual".
If you look at the layout of the house, the room known now as "Lizzie's room" that opened directly to the Master bedroom, was originally Emma's. I also read that when Emma had the room, the door was not blocked. It was only when Lizzie got older that she traded rooms with Emma, Emma moving into the smaller room and Lizzie taking the larger room that connected with their parents room. It was only after Lizzie took this connecting room that the door was then locked and blocked with a desk. Since Lizzie is generally regarded as the one with the stonger personality, I sincerely believe that she was trying to protect her sister from their father.
I agree that neither one was heartbroken. I think they were more relieved that the oppression would stop. The person that abused them, their father and his wife who allowed it to occur were gone.
I just think that Lizzie had gotten to a point where she just couldn't take it anymore. First the abuse, then getting written out of the "new will", Andrew also supposedly killed her pidgeons (she had a coop of them). I think she just snapped. I think that is why she tried to buy the poison. I think she just wanted it all to stop. Poison is a very passive way to kill someone, nonconfrontational and a favorite of women killers. Whether she was able to buy prussic acid from another druggist or if she used some ineffectual poison the day before that caused the "food poisoning" we'll never know.
I think this is also why when the Borden's died, the neighbors rallied around the girls. I think they knew "something" was wrong in the Borden family, but abuse be it physical or sexual was not talked about in Victorian times. You minded your own business and a man had a "right" to hit his wife or children. I think the neighbors understood why it happened...but yet when the trial was over, Lizzie was still either a) a murderer b) in on it and that was why she went from being a cause "celebe" to pariah.
As far as Lizzie being either naked or wearing a rain coat...I don't think that was really necessary. If you go to the Fall River Historical Society, they have the white bedspread on display that was on the bed that Abby was making when she was killed (still unwashed). Dispite being white and only inches away from where Abby was hacked to death, there was VERY little blood splatter. It astounded me that someone who was hacked to death with almost 20 blows would not give off more splatter. Other than the large pool of blood under Abby, I'm not sure exactly how much total splatter was visible in the room. This is why I think that Lizzie was wearing the dark dress that her friend Alice saw her burning a few days after the murder. Andrew received fewer blows and there was supposedly only a few lines of blood splatter up the wall and a few drops on the ceiling. Most of the blood would have been flung away from the killer I really don't think that unless they hit an artery where the blood spurted out onto the killer, the splatter on the killer would be less than what you might think. It was also mentioned that Lizzie's closets were NOT searched. This is because all of the police men were MEN and due to Victorian code of conduct they could not search her or her personal closets for fear of seeing her underwear. (it didn't matter if she was in them or not) She could have easily slipped back upstairs, slipped off the dark colored dress, hid it in the back of the closet, pulled another one over her head, wiped her face/hands and called for help...in just a few minutes.
I did read somewhere (forgive me I'll have to look it up to quote the source) that ONE small drop of blood was observed on the white petticoat under her dress but that as it was "that time of the month" she was questioned no farther about it, again, due to the Victorian code of conduct.
these are just my conjectures based on all of my reading/research as well as my impressions of the property so take them for whatever that's worth.