Look -- in a murder investigation it is very helpful to have the body. And in an attempted murder -- some evidence of a person coming close to death. Here, Terri's collapse is that evidence. The collapse is not sufficient evidence, but it is a strong piece of evidence itself, since it is unexplained. That "unexplained" is usually translated as suspicious, especially when circumstances such has Micheal's later murderous promise-keeping, and the his excessive odometer angst are included.
No, despite your illogical attempts to make it so, it isn't.
A body is just a body. A collapse is just a collapse. Unless there is some EVIDENCE of FOUL PLAY. In this case, there is NONE. The fact that she collapsed, in and of itself, is evidence of nothing other than that she suffered cardiac arrest.
And in an attempted murder -- some evidence of a person coming close to death. Here, Terri's collapse is that evidence.
You really don't get it, do you? You are ASSUMING that it was an attempted murder, and then using the fact of her collapse as 'evidence'. This is an example of the logical fallacy known as the circular argument.