It was already said that violent crime rates are actually higher in rural areas than urban ones, but it should also be mentioned that areas with high minority populations, especially black communities, are more heavily policed.

In addition, studies like this one (https://onlinelibrary.wiley.com/doi/full/10.1111/1745-9125.1...) have found that the relationship between crime rates and undocumented immigrants actually decreases

As someone who came to America undocumented at the age of 5, my personal intuition is that undocumented people tend to be more fearful of authority and therefore more likely to avoid getting in trouble