He just so happened to buy shackles and handcuffs days prior,
And was her DNA on the shackles? Was her DNA on the bed or anywhere in the room where Steven supposedly locked her up? Where Brendan "says" they stabbed her, and at one point (after being heavily pushed in that direction by the police) says Steven shot her?
You're as stupid as the prosecutors. You find this vague barely-there "evidence" but have absolutely no cohesive story to explain what happened.
A key found in his room with no DNA of Theresa and no explanation of why Steven would bring the key to his room at all.
A bullet found in the garage with no blood on it and barely enough DNA to run 1 test. But no blood found in the garage itself so when that comes up later our story will be that she was shot in the car.
Her bones found behind his garage, right in his burn pit, a damning piece of evidence! Except they were moved there, and bonfire could not create the amount heat needed to burn the bones as fully as they were. And bones found in 2 other locations with no explanation of why Steven would either A) move those bones if the pit behind his garage is the original burn spot, or B) move the bones back behind his garage if there was another burn location.
All anecdotal evidence, wrapped in the suspect intentions of the people "finding" them, and all without any reasonable or logical story to connect them.