I'm sure I'm 20 miles behind already but I'm pretty sure the trained medical staff at the hospital would know the difference between dirt and injuries. It has been said she was treated for non-life threatening injuries. I can't understand why this is still a question for some people.
As for the statement given by her sister, I think the only people confused by that are the ones that were looking for something. She made it clear she wanted to read a statement FROM her sister and husband, thanking all those who helped. I think her only mistake was allowing questions after, to which she was unable to answer, for the most part. I suspect allowing the questions was likely suggested to her from someone else, as a gesture to the media, since it's SUCH a messed up, high profile case.
fwiw.