A geographic profile of the five canonical victims of Jack the Ripper. Click on the image to view its high quality version.
The case notes that follow do not attempt to use the above geographic profile to make any claims about the Ripper series or support any specific theory. What follows provides an overview of the thinking that went into creating the profile in order to serve as an educational case study for law enforcement who may be tasked with interpreting and applying geographic profiles to investigations.
Creating a geographic profile of Jack the Ripper‘s hideous work proves an interesting challenge—not the least because the identity of history’s most notorious serial killer remains a mystery over a century later. It poses a challenge because the distribution of crime scenes is fairly uniform and takes place over such a small area.
Geographic profiling is nothing more than a sophisticated version of the old-fashion police technique of putting pins in a map and looking for the offender somewhere in the middle of the pins—albeit, refined quite a bit with psychology and empirical observation. Due to the nature of the geographic profiling model, an even distribution of crimes scenes will yield a profile little more helpful than looking somewhere inside the the polygon created by the outer crime scene locations (called a convex hull); it’s the irregularities in the spread of crime scenes that reveal the most about where the offender may live. While not a perfect circle, the Leather Apron committed his horrors in a rather nondescript, uniformly-spaced distribution.
Jack presents us with another challenge: he stalked, killed and mutilated his victims over such a small area. Strictly speaking, the smaller the hunting grounds, the less opportunity the offender has to live1 within the boundaries of his crimes. Unfortunately, today’s geographic profiling models only make predictions within the convex hull of an offender’s crime scenes.
A Lucky Break
However, let’s assume for the moment that the offender did live within the area as suggested by a 1988 FBI profile. In this instance, the constricted hunting grounds turn out to be a lucky break that helps us overcome the difficulty of a uniform crime scene distribution. If Jack avoided killing too close to his home—for fear of being recognized and to prevent drawing the investigation to his doorstep—then there were only so many places left in the Whitechapel where he could kill. To a geographic profiler, that translates to effectively reducing the number of possible locations for his residence.
Operating under this assumption, I created a geographic profile that incorporates this idea of a buffer zone, or area around the offender’s home where he avoids committing crime in order to avoid detection and capture. Specifically, I modeled Jack’s behavior in the following manner:
- Jack would not kill right outside his home.
- The probability of Jack killing would increase with distance from his home until it peaked at some point.
- The probability Jack killing would then decrease with further distance from his home.
The resulting geographic profile is pictured above and can be viewed in its full size here.
A Very Real Alternative
As with everything Jack the Ripper, the above geographic profile is not as cut as dry as it may first seem, leaving plenty of room for contention.
One of the first decisions a geographic profiler must make is whether or not the case is appropriate for analysis. The model makes certain assumptions about the case and cannot make correct predictions if these assumptions are not met. One of the fundamental assumptions of geographic profiling is that the offender is a marauder, meaning he commits his crimes outward from his home in areas he frequents during the course of day-to-day life. A commuter, on the other hand, travels some distance to commit crimes in an area he does not visit during routine activity.
While it is still impossible to predict whether an unknown offender is a commuter or a marauder (although promising research into this problem is currently underway), there are some situations that force an offender to operate as a commuter. If one of these situations is likely, then we can predict that the offender is a commuter.
The geographic profiling model assumes that the availability of victims is uniformly distributed through space. Jack the Ripper’s five canonical victims were all prostitutes. While it may have been possible to find prostitutes anyway in the London metropolitan area, it is my understanding that Whitechapel featured a relatively extreme concentration of poverty-stricken unfortunates. Consequently, Jack the Ripper may have been forced (at least highly motivated) to travel to Whitechapel to commit his crimes in order to find the best selection of victims.
As a result, it is next to impossible to determine whether he killed in Whitechapel because he lived there or because he had to travel there for the best hunting grounds. If the latter is the case, then the geographic profile is invalid. In fact, this modus operandi is not even uncommon. Many modern day sexual serial killers travel to red-light districts to pick up prostitutes to kill and mutilate. Given this type of case today, a geographic profiler would tell police that he or she could not validly profile the case.
A Note to Ripperologists
I am by no means a ripperologist. I have only a basic knowledge of the case, and have not committed to any of the theories. Furthermore, I doubt I have offered anything new to the debate. In fact, my geographic profile agrees to a a certain extent with D. Kim Rossmo‘s geographic profile of the case, which is to be expected since we use similar models. However, if you have found this profile at all interesting or useful, feel free to post it in your discussions and articles. You can even crop the image down to the probability map itself without the surrounding interface. I just ask that you give me credit with a link to my website.
1. The location that an offender operates out of, called an anchor point, is not always his home. It is any place from which the offender leaves to commit a crime, returns to after committing a crime, or both. I use the words home and residence to avoid jargon but with the recognition that Jack the Ripper’s anchor point could have been a workplace or favorite public house.