For law enforcement, a lot of “GIS” begins on the street as police officers generally possess an innate knowledge of what areas on their beats are trouble spots. Those who are back at the office and doing crime analysis don’t have that field knowledge, however, they can identify hot spots with the help of:

• Maps and Geographic Information Systems”
• Statistical Tests

http://crimeinamerica.net/2009/10/26/hot-spots-key-to-crime-control/

Here’s an idea: What if the GIS could include the so called “ground truth” gathered by police officers, as a specific sort of user-generated data?