A little detail on that case that Steelers fans like to forget: There was potential evidence, but it was conveniently destroyed.
After the girl went to the police, the police went to the club where the incident took place to review the security footage. They hadn't started when they were called away on another matter (only police in town, I guess.) When they returned, the security footage had been "accidentally" erased with no way to retrieve it.
Based on the standard everyone applies to the Patriots, this couldn't have been an accident and could only have been done intentionally to conceal Ben's guilt.