The police are so incompetent it's not even funny. You can serve all the info they need on a silver platter and they won't move a muscle.
I once had a friend who was being harrassed (keyed car, 100's of calls and texts per day, guy would text info that could have only been known by stalking them) and the police refused to do anything at all. We knew who was behind it and the anonymous call/text apps the harasser was using had an abuse@servicename.com email for police to use. They flat out refused to do anything at all.
We were able to get my friend's number blacklisted from a number of these services on our own but the harasser would just find a new service and start over again.
In the end the harassment stopped only after another friend confronted the harasser, called the most recent number, had the guy's phone start ringing, and told them stop. First it was incredibly dangerous to confront someone like this and I guess we were lucky he backed off since even with that "proof" the cops wouldn't have raised a finger.