Rabbis are many wonderful things. They are not police officers. They don’t know how to investigate crimes. They don’t know how to collect and preserve evidence. They don’t even know what constitutes a crime.
Police officers are not educated in halacha. They can’t teach Gemara. They don’t officiate at weddings or perform brises. They don’t convict people of crimes. But they are trained to recognize and investigate possible crimes, collect evidence, preserve it, and give it to the District Attorney who determines whether criminal charges are appropriate according to the laws of the State.
Reporting a disturbance or something which you believe might be a crime is your civic duty as an American citizen. It doesn’t mean a person is guilty. That isn’t your call or the police officer’s. It is the only way the Justice system can determine if there might have been a crime and carry out its legal duties to investigate criminal activity.