Except the body, of course.
Your statement that the police didn't find anything has no force because they didn't search thoroughly and effectively in the first place. You can't find anything if you don't look, y'know.
What the police said, roughly, was that they didn't find any furniture knocked over. Big deal. Michael was more than twice Terri's size. He could have handled her like a rag doll. He didn't have to knock over any furniture -- if indeed there was any furniture in the hallway and bathroom door, where she was found.
Suppose there had been some evidence of a struggle. The police didn't do forensic tests that could have determined whether Michael cleaned up any mess before they got there. That's why the lack of forensic testing gutted their findings.
The police, in short, did more or less nothing. And that is what you rely on in your judgments -- the same nothing.
Police generally aren't going to do a thorough forensic search unless there is a death. At the time, there was every hope that Terri would recover and anything could have been cleared up then.