That was a very hard sentence to read...which is rather ironic in this case
I am willing to say it is possible he did it and Dassey told the truth. Problem is literally none of the evidence corroborates it. (especially Dassey's confession which is all over the place and proven wrong on facts) It doesnt take a genius to convict the wrong guy (see: already did it to Avery once) using weak evidence so it isnt like they had to do that much work. There is a reason it doesnt seem to stand up to strict scrutiny.
This is not CIA level stuff...the hardest thing they had to do was sneak a Rav 4 on a 40 acre lot or whatever when no one is really around. The cops have already shown the lengths they will go to convict him (including keeping him in jail when other agencies told them he wasnt the guy) so that isnt very hard to do.
What that you saw makes you think he did it?