We all know Ben was at the club. Whatever rape kit was used was used to fit this particular charge---sexual assault. That means no vagina swab can be used or is admissible. This isn’t rape it is sexual assault. That means that the alleged victim is admitting that there was no sexual intercourse. This leaves us with the fact that any and all evidence that is on the victim’s body or in the clubs bathroom can only imply that Ben was there. A simple strand of Ben’s hair could have fallen onto the floor or onto the victims shoulder after a polite hug or hand shake. This is called circumstantial evidence. Is the evidence a sample of Ben’s sperm? If it is that does not prove Ben assaulted this woman. Ben could have simply masturbated on his own in the club’s bathroom. Without a witness or any video evidence, there is absolutely no way the prosecution can prove any sexual assault. They have no case. And this is why there are no charges. What they have been waiting for all this time is that a witness could come forward or Ben would somehow implicate himself.
Circumstantial evidence is best explained by saying what it is not - it is not direct evidence from a witness who saw or heard something. Circumstantial evidence is a fact that can be used to infer another fact.
Indirect evidence that implies something occurred but doesn't directly prove it; proof of one or more facts from which one can find another fact; proof of a chain of facts and circumstances indicating that the person is either guilty or not guilty.