"Father" was employed at the same place as when they filed for bankruptcy.
He worked a night shift, so the whole family lived on his schedule. It just so happened that this schedule was also convenient for torture. Perhaps he selected that schedule for that very reason. This means that the "mother" was home alone with the children while he was at work. Additionally, he had a long commute, of over an hour each way, which added to more time with just "mother."
This leads me to believe that perhaps she was the lead in this horror show, and convinced him to go along with it. Forgive me for this walk down assumption-stereotype lane, but if he was a "nerdy science geek" in High school (as he was described by fellow classmates in msm), and in his early 20s he got Louise as his wife, he may have been completely smitten with her and so grateful to have her that he did anything for her. I'm thinking of the vow renewals, and him getting all teary, and the besotted way they looked at each other. She made him the center of her world, and as a result she was able to do anything she wanted, including torture their children. They are both complicit, both monsters, and both should get everything the DA can throw at them (it will all stick, IMO). But I am leaning towards LT being the original source of this evil.