Could be, I certainly don’t know. A good defense attorney (not “good” that way, of course) could posit that he had only the strength left to position the pillow. Once again, I look at computer screens for my news and therefore probably know less than I used to.
Also lack of autopsy does not necessarily mean lack of toxicology screen. If I croak, I want that to be done, even if only to figure out if I had botulism poisoning or something like this.