Alec Wilkinson writing for the New Yorker:
By reading meaning into the geography of victims and their killers, Hargrove is unwittingly invoking a discipline called geographic profiling, which is exemplified in the work of Kim Rossmo, a former policeman who is now a professor in the School of Criminal Justice at Texas State University. In 1991, Rossmo was on a train in Japan when he came up with an equation that can be used to predict where a serial killer lives, based on factors such as where the crimes were committed and where the bodies were found. As a New York City homicide detective told me, “Serial killers tend to stick to a killing field. They’re hunting for prey in a concentrated area, which can be defined and examined.” Usually, the hunting ground will be far enough from their homes to conceal where they live, but not so far that the landscape is unfamiliar. The farther criminals travel, the less likely they are to act, a phenomenon that criminologists call distance decay.