All areas have their fair share of crime, but San Tan Valley homes are typically cheaper because they are so much farther from the city. Most of them are at least 13 miles to the freeway and then another 13-15 miles to the city areas. The land there was cheap when the builders bought it and they passed on the savings to the buyers.
When it comes to any safety/crime related issues, it's always best to contact the local police department with all your questions, hear all there is to hear firsthand. If unfamiliar with the area(s) do revisit more than once and at different times of day, possibly chat with locals/neighbors. Real estate professionals are prohibited from steering, enticing a buyer to purchase, or not, in specific neighborhoods. http://www.neighborhoodscout.com/ https://www.crimereports.com/ http://www.homefair.com/
Usually the best source for accurate neighborhood crime and safety information can be obtained throught he local police department or county sheriff's department. They have access to the most current and accurate information and are generally willing to be helpful.