Steely, I'm glad you got the report. I know you devoured it, even as you hated the inconsistencies. And I'm glad you let us know. I was wondering when you would get it, and what it would say.
I like the ideas that Marg came up with, and I also like your idea that she could have gotten into an argument with-a friend and just stumbled off in anger. But that's why the police hate cases like that. They're just too difficult.
I'm one of those leave-no-stone-unturned kind of folks (much to my husband's dismay--he calls me a pit bull and I just hate that) so I'd end up making an appointment. with-the coroner. S/he could at least explain some things that may be obvious afterward, but that you didn't think of, and give you some answers, such as whether the bruises could have appeared b4 of after. I have no idea if they take appts or how busy they are but it's worth a try.
You know eventually that you'll find peace whether your sister died by accident or not. It's going to take a long time. {{hugs}}