This next is out there but bear with me, try this theory on for size:
You have a group of people who seriously messed up, and they are sued for a lot of money-and if this lawsuit prevails, in addition to the loss of finances, they might also lose their jobs, their standing in the community, etc. Plus the person suing them, is someone they despise.
Perhaps if placed in this position, one might lie in wait for for the person suing to screw up. Maybe in that position someone might even employ a sort of "spy" from within that target person's close social network, to watch for that person to make a mistake, one that might render a victorious lawsuit impossible.
But here's the hitch, the target person lives clean. They have a girlfriend who they don't cheat on. They don't drink, do drugs, gamble or so much as fail to stop at a red light.
What if Scott Tadych was paid to alert LE if Avery committed any act that would discredit him? When Avery fails to do produce this, either Scott on his own, or under the guidance of whoever he is helping, sees Teresa on the property one day and gets a big idea-Approach her! Offer Teresa money to say she was molested or raped by Avery on a photo-shoot, presto, now Avery is a rapist again-lawsuit impeded or gone. And in Scott's mind, since he is being paid, others will sign on just for the money.
But Scott can't just call Teresa, he needs to meet her in person, so there is no phone record of his having spoken to her. So, by way of Barb he arranges for Teresa to come out to the property and take pics of Barb's vehicle (it was Avery's sister, not Avery, who had a vehicle to be photographed-Avery was just facilitating the shoot)
And Teresa does show up, but after she takes the pics and makes her exit, Scott follows her, waves her down, and engineers a place off the road, out of general view, for them to stop. He approaches her with the offer. She not only declines, she is angered. There is an altercation, and she is killed at the back of her vehicle. Ergo, the blood splatter on the rear door.
And then the rest is just in keeping with the original plan, only now the entire scenario is in the control of those anxious to frame Avery. Tadych would have had easy access to Avery's trailer. Maybe Bobby was part of the plan as well, or was brought in later and assisted...
Again, this theory is a little elaborate. But what if...