Here's the thing though - NONE of Brendan's potential stories match up with any of the evidence that we know are factual. Even if you just take Brendan's confession for being factual, you would still have SEVERAL things you'd have to prove, such as:
-The knife used to carry out the actions Brendan described is no where to be found.
-None of her DNA is found in ANY location on the property, outside of the bullet in the garage, and the pooled blood in the back of her trunk, and the burn pile in the backyard (obviously).
What we do know is that, wherever she did die, she bled, and profusely at that. How do we know? She left pools of her own blood in her own car, which was an obvious transport to where she was burned. At the very least, she was killed at a location, then transported to another location, and we know she was bleeding. The fact that NO blood is found anywhere on Avery's property, on none of his clothing, other than her car, not even in the location's Brendan calls out in his testimony, means that either Steve Avery is a master of forensic investigation techniques, or that Brendan was lying.
And before you say that the evidence (clothing, bedding, knife) could've been destroyed in the fire, realize that there still would've been traces of those things in the ashes. If they still had her bones & other things in the ash pile, they would've found other things in that pile as well, and we would've heard about it.