I'm sure the investigators have a handle on the dynamics of the family and the relationship between TS and AS, as well between TS and Gannon. They've interviewed all of them, and they've seen the public on camera video of TS and her weird behavior. They've also no doubt received rebuttal from AS and mom (can't remember her initials!) about her claims in the video. And AS has likely filled in some blanks about what he saw on the neighbor's video as far as the demeanor of both TS and Gannon, and other nuances. I'm guessing there may also be more to that video, either in footage or clarity, that we're just not able to see.
A couple of things -
First, she has really piled onto herself and added a lot to reconcile in the gap in time between leaving that driveway, and even the hour between 2:15 when she got home, and 3:15 which she gave as the earliest portion of the timeline for going to the (imaginary nameless) friend's house.
It's going to be hard to say she got gas, grocery shopped, had her nails done, went to yoga, or whatever, between that morning and when she returned, because where are the receipts, does she appear on camera in those venues, do people who served her or checked her out remember any of this, where was Gannon while she was doing these things, and on and on it goes. She never thought that anyone would see her in that driveway with Gannon, and that's a beautiful thing, because she's created a huge dilemma of having to explain where she was, where he was, and lining up moving parts with proof of those parts, when she simply can't. If she didn't think about neighborhood cameras, she didn't think about creating an alibi past that driveway, most likely.
As re: family dynamics and who has responsibility: If there is Narcissism in this equation, and I mean the full blown personality, not just self-absorption and self-serving priorities, there is a level of psychological violence and manipulation in that home and family that is literally mind-bending to all parties, including the adults. Narcissists are masters of brainwashing even the most functional adult, because they groom people, they lure, they love bomb, then they devalue, then they gaslight to rebut the devaluing ("I didn't say that"; "You're imagining things"; "I think you're overreacting", "No, I didn't say that, I said x, and you were really distracted that day and just don't remember...can I fix us some dinner, you seem exhausted from work", etc., etc.). The purpose of all of this is to keep the victims off balance and feeling like this loving gushing person can't really be lying or cruel, 'and besides, she's right, that day I was really distracted...'
I've witnessed this, and children are so tragically vulnerable to the confusing happy good mommy/mean mommy switch up, and so reliant on the person for care, they can't sort that it's abuse, and they don't report, or, if they do, the person they tell is under a spell as well, and can't see into it fully. It's always the manipulated person's fault anyway because they upset the other party (look how hard she's tried and is keeping the family together while the other parent is away), and so on. There are volumes written about how these people puppet other people, using psychological tools of harm that normal people have never considered because we're normal and don't see other humans as objects. So, no, because you marry someone, live with them, and talk to them every day, you're not necessarily aware of what's happening at all these other levels, and certainly not when you're away from the house. As adult might know something's 'off', or suspect dishonesty, but then there's always something to override the perception. Gaslighting is a very vicious and powerful tool of abuse. And everyone is a victim in a home where any narcissist lives. Triangulation is one of their favorite tools so all family members are pitted against each other, the children have special secrets and information that their siblings don't have, the parent 'needs' their help, and it just goes on forever. These people destabilize families and homes to keep ongoing control of their human puppets. Up is down, now it's sideways, it's sunny when it's raining, and everybody else is just confused or even 'mentally ill' if they counter this false reality. Don't know if this is the big picture, just saying if it is, this is why it appears on the surface that someone should have 'known', when it takes a crisis and a tragedy for the mask to fully fall off.
I think of ownership and accountability as who gets to eat the pie. I believe that while there may be some slivers and bites anyone could feel is theirs to swallow, because guilt is powerful thing looking back, there's only one person who will be seated at the table of accountability with a pie and a big spoon. (barring third party assistance, and they have their own pie) JMO
