Assuming Lizzie was actively involved in the Borden murders, then something sparked her to take action to end their lives. I agree that the primary driving force was lifestyle dissatisfaction. That said, it would be safe to say that a huge majority of humans throughout history have longed for bigger and better. While most will handle this desire by trying to get a better job, accepting reality or wallow in jealousy and envy; a very very small fraction take criminal action to better their lot in life. Embezzlement is bad, but no one has their life ended. Killing to accelerate an inheritance or to receive life insurance proceeds is pure evil and is a strong indication that the killer is extremely self-centered. They decide that their happiness is more important than someone else's life. That is why I think Lizzie had to have had a Narcissistic Personality Disorder.
Since John Morse had previously and inappropriately told the sisters about AJB's Last Will & Testament, I imagine it was John that also told Emma & Lizzie about the Fourth St. purchase. AJB shared his business dealings with Morse. I think Emma always despised and resented Abby and used her sisterly influence to convince Lizzie that the transaction was wrong and that Abby was a bad person. With the seed planted, Lizzie spent the next five years becoming more and more dismissive of Abby. Along with that emotional transition, I suspect Lizzie also became emotionally detached from Andrew.
In my opinion, Abby, trying to make sure her half-sister didn't lose her home was appropriate and not worthy of criticism. Lizzie's opinion of the arrangement didn't and shouldn't have entered Abby's thinking when she made her request to Andrew.
Same goes for AJB. To our knowledge, he never engaged in physically hurtful conduct towards his daughters. He enabled them to live a worry free life with no responsibilities. He was almost 70 years old. His father lived to 80 years. So if they just waited another decade if would all be theirs. But Lizzie didn't want to wait. If she was the killer, she owns 100% of the blame and responsibility.
Lorcan wrote: Mon Apr 20, 2026 8:25 pm I blame Andrew for not spending less than 1% of his money on upstairs bathrooms, valuing his Yankee Puritan ego over his daughters' comfort and dignity. I blame Andrew for not buying a house like Maplecroft and leaving it in his name, if ego needs be, (just 4% of his money - a simple real estate investment and he could have let 2 middle-aged women live there without a man of the house. I do not buy the social convention argument - there were many widows of the civil war and wealthy unmarried women in that neighborhood at that time, including Emma and Lizzie just months after the crime). Andrew chose to live by his rules. Andrew chose to dole out a $4 per week allowance. Andrew chose to never let Lizzie have the dignity of a private door. Andrew chose to not tell his daughters what he had done when he bought the half-share of the house for Abby's half-sister.
I blame Abby for advocating for Sarah to get a house when Lizzie's bedroom was the size of Abby's closet. I blame Abby and Andrew for the humiliation, betrayal, and loss of influence Lizzie felt when an outsider told her that her parents bought half the house for Sarah, a woman 2 years younger than Lizzie.