Crime prevention is not a technical systems responsibility. It is everyone's responsibility. There are very few times, that criminals stick around for the police to show up and then initiate the criminal act. When criminals realize that this system can monitor their activity, they will either move to another area, or realize the futility and give up the activity.
In the MA town that I worked, the police also operated the Ambulance Service. One early morning, while we were enroute to the hospital with a heart attack patient, with everyone except the dispatcher inside the ambulance, we drove past a jewelry store that was being broken into.
Cops cannot be everywhere. But, how do explain the down turn of violent crime in cities?