The two witness rule
The problem with Watchtower is they stop when there aren't two eye-witnesses. But often there is a second witness in the form of forensic evidence that only professional investigators (police) can find, if they get to it in time.
Anthony Morris claims Watchtower doesn't discourage going to police, but they don't encourage it either. And in a way they do discourage it, not in writing in a Watchtower magazine, but by the elder's counsel..."You wouldn't want to bring reproach on Jehovah's name, would you?"
There are ways of discouraging going to the police besides directly saying not to, and a "second witness" is lost as a result.