Another factoid not mentioned in the documentary:
Brendan told police Teresa was handcuffed to the bed and her legs were in leg irons, connected to the bed as well.
Here's what was not told to the audience watching the documentary: In Avery's bedroom closet police found handcuffs and leg irons.
If others have responded to this then sorry for the duplication.
You need to take this information in reverse order to which the police are stating.
The cops found handcuffs and leg irons in the bedroom, and then fed that info to Brendan during the interview/interrogation.
There is no evidence she was ever on that bed. If she was held there by handcuffs and leg irons, and her throat cut, there would be blood spatter everywhere, blood pooling on the mattress, and skin DNA on the handcuffs and leg irons.
As far as I've read, none of this evidence exists. Please correct me if wrong.