Found this video that features a long interview to Prof. Alan Frazier on the subject of drone usage in law enforcement, in which he also answers questions from the public.
Prof. Frazier has a very particular curriculum, as he is both a Professor at the North Dakota University, Department of Aviation and Deputy Sheriff in the Grand Forks County Sheriff’s Department (link). This puts him in a strong position to deeply understand the technical and legal background of quadcopters, multirotors and more in general UAV usage, and to apply this knowledge in the field, as a law enforcement officer. For these reasons it is of particular interest to hear his views on the subject of UAV and law enforcement. Here’s the video:

For some quick examples of how drones were used recently by Prof. Frazier in the field, see this article