CRIME STATISTICS / INFORMATION
These web sites provide crime statistics and studies, and may have information concerning the area of the home you want to buy. Note that the police departments for the various municipalities also provide crime statistics, and may provide different information from the private sites.
Compare City Crime Rates (private site):
http://www.azcentral.com/CrimeMaps/
Scottsdale Police Dept., Crime mapping tool 
Felon Search (private site):
Crime Prevention and Statistics (private site):
Arizona law and crime information (government site):
Arizona sex offenders (government site, list available for a fee):
Former drug labs: