How to best use geographical information as a factor?
If you are predicting crime rates in a certain region, we may use clustering to deduce useful information. In clustering, basically, we will try to group similar data points together and treat them as a single class. We can understand this with an instance.

We have various points ( Latitude and Longitude ) and each of them represents a certain type of crime. Even by mere observation, we can conclude that some specific types of crime occur in a particular region only. Basically, we are going to cluster such points which are in the vicinity of each other and belong to the same class ( kind ).


  For example, an emergency call from an area ( with more cases of robbery ) arrives, the probability that the victim has also suffered from the robbery is more than any other crimes. 


As we get more data, we can retrain our clustering algorithms to make more clusters and thereby increase efficiency.