It wasn't up to the coroner to analyze or speculate about fiber or DNA evidence. Nor is it the coroner's job to speculate on the killer or who may have staged the crime scene. That is for LE to determine. But he should have been able to state a TOD and tried to be more clear about which of the two causes of death killed her.
He should have been clearer about what may have caused hymenal erosion, bruising, hyperemia and bleeding in the vaginal area of a 6-year old girl. Not that he had to state WHAT or WHO may have penetrated her, but those conditions are NOT naturally occurring. He should have been clearer about those conditions being CAUSED rather than simply being "noted". The "who" and "what" would be for LE to determine. But let's start with being less ambiguous about what was very likely sexual contact. NOT bruising and erosion from "bubble bath" or child masturbation (which, BTW, does not involve penetration, but rather rubbing of the external genital areas-little girls don't "penetrate" themselves for pleasure- some info for those with a propensity for imagining JB doing this to herself (to the point of bleeding and bruising)- it doesn't feel good to have ANYTHING stuck up your vagina at that age.). Let's call a spade a spade.
He should have been more thorough in his examination when first encountering the body in the living room that evening. And he should have used ten sterile nail clippers instead of a single unsterile nail clipper for the autopsy, thereby forever contaminating the results of that testing.