Do dark skies increase crime? I think not. After all, criminals need to see, to "safely" commit a crime. And if they have their backs to a glaring, unshielded light, and the victim is walking toward it, with impaired vision as a result, the criminal has the advantage.
I have recently seen articles that show law enforcement's reaction to a crime is to warn people against darkness. At the local state university, several robberies took place in the dark early hours of the morning. The safety office issued a warning to all students and employees, not to avoid early morning hours when few people are around, or to walk in groups if they must be out at that time, but to stay in well lit areas. I called the office and was told that the crimes occurred on streets with streetlights at every block. The spokesman insisted that darkness was a factor because the crime took place at night, and that the incidents occurred between the streetlights, rather than directly under. For generations, the immediate reaction to crime has been to increase lighting without any real data to back up the reaction.
In my own home county of Powhatan, there have been recent daytime burgleries of residences. One of the main suggestions included in the article, by law enforcement, was that people should light up their houses front and back, as being one of the best ways to repel intruders. Where is the logic in that? These were daytime burglaries.
A recent petty crime took place at a local gas station. A blogger wrote in following the article that this was surprising, considering how well lit the parking lot is at night.
Of course I know that concealed source lights are needed, when working or walking outside at night, for safety reasons. But lighting areas as if to help guide in aircraft, to prevent crime, just isn't logical, from my own observations.