The only problem with "letting it go" is that there's a lot of circumstantial evidence that Terri was strangled by her husband. If you're the governor of a state, how do you just let that go? The people who are appalled by this investigation are the same kind of people who strongly support capital punishment even though there is ample evidence that many innocent people have been wrongly convicted of capital crimes. Either you defend life in all cases or you do not defend life.
The autopsy did not show this. But why worry about medical science, I mean, you have a "feeling" it happened and so that is enough for you.