I suggest creating a dangerous areas alert feature as slums, streets or dangerous areas, with danger degree (high, medium or low) for assault, burglary, vandalism, etc. And the system always warn approach. The user can configure whether you want a route that deviates from the area or not, as you prefer the user.
Agostinho Serrano commented
I vouch the idea. A number of occasions waze has sent me thru slums or even poor communities that are really a bad idea to cross with a car (if you don't belong to such community). I suggest the option to use or not use "criminally safe routes all the time" as reported by users. For sure my wife, for example would toggle the option and I wouldn't much. Add a report of "mildly unsafe/um pouco inseguro", "certainly unsafe/certamente inseguro" and "quite unsafe/muito inseguro" and just let the community do its part.