In all honesty, we do not know what they have. I think we got what the SPD wanted us to have when all of the information was posted. It's certainly possible that they have a witness who saw the whole event occur, we just do not know at the moment. Just because they won't come forward in the media doesn't mean they do not exist.
~jmo~
I don't see anything to suggest they have a witness that saw the whole event from the start. The "charging document" doesn't have any new info.