Geographic Profiling of Serial Murderer, Gary Ridgway, to Assist Law Enforcement in the Apprehension of Future Serial Murderers Rachel Neldner Department of Resource Analysis, Saint Mary’s University of Minnesota, Winona, MN 55987 Keywords: Gary Ridgway, Green River Killer, Serial Murderers, Law Enforcement, Geographic Profiling, CrimeStat III, Spatial Description, Spatial Modeling, Probability Maps, Mean Center, Center of Minimum Distance, Standard Deviational Ellipse, Journey to Crime, JTC, Predictive Analysis Abstract This research focuses on the geographic profiling of a serial murderer for the purpose of assisting law enforcement in the apprehension of future serial murderers. Serial murderers have distinctive characteristics and hunting styles which distinguishes them from other offenders. This case study focuses on the study of the Green River Killer, Gary Ridgway. Ridgway eluded law enforcement capture for nearly twenty years. He was eventually captured through DNA linked from several crime victims. This research examines spatial description of incident data using the following functions: (1) Mean Center; (2) Center of Minimum Distance; and (3) Standard Deviational Ellipse. Also, this research examines incident data using spatial modeling – the Journey to Crime (JTC) estimate/probability map. It is hoped this analysis will help law enforcement to narrow search areas for future offenders. Geographic profiling results can impact an investigation by suspect prioritization, patrol saturation, neighborhood canvasses, police information systems data contained within police database, and DNA searches. Introduction can be used to assist in deciding which cases are capable of being profiled as well According to Rossmo (2000), knowledge as improving profile accuracy. gained through research and experience of how and where criminal predators hunt for Serial Murder victims both have practical and theoretical implications. Investigative efforts can Brooks, Devine, Green, Hart, and Moore produce large numbers of potential (1987), define serial murder as a series of suspects, often totaling into the hundreds two or more murders, committed as and even thousands, which cause problems separate events, usually, but not always by with information overload (Rossmo, one offender acting alone (Rossmo, 2000). 1997). Along with information overload, The crimes may occur over a period of high costs associated with any extensive time ranging from hours to years. The long-term investigation justifies the need Federal Bureau of Investigation (2008) for research in the area of geographic defines serial murder as “the unlawful profiling (Rossmo). According to Paulsen killing of two or more victims by the same and Robinson (2009), research seeks to offender(s), in separate events” with a time develop simple spatial diagnostics which period between murders. _________________________________________________________________________________________ Neldner, Rachel. 2015. The Geographic Profiling of Serial Murderer, Gary Ridgway, to Assist Law Enforcement in the Apprehension of Future Serial Murderers. Volume 17, Papers in Resource Analysis. 22 pp. Saint Mary’s University of Minnesota University Central Services Press. Winona, MN. Retrieved (date) from http://www.gis.smumn.edu Serial Murderers’ Hunting Typology regarding times and locations of the crimes, the greater the likelihood the case Predatory criminals employ various will be solved (Rossmo, 2000). Crime hunting styles in their effort to seek out locations provide evidence and witnesses; and attack victims. These, in turn, affect time of offender allows suspect alibis to be the spatial distribution of the offender’s verified or refuted. Together, they permit crime site, suggesting that any effort to investigators to establish if the victim and predict offender residence from crime a suspect were in the same area at the locations must consider hunting styles same time (Rossmo). Keppel and Weis’s (Rossmo, 2000). While murder can study broke murder down into five potentially involve several different types potential different locations: (1) victim last of crime locations, experience has shown seen site; (2) initial contact site; (3) initial the victim encounter and body dump sites assault site; (4) murder site; and (5) body are most important in terms of an recovery site (1993). The initial contact investigation-oriented geographic analysis site and body recovery site are the most (Rossmo). important in determining where the According to Rossmo (2000), the offender residences occurs (Beauregard, serial murderers hunting process can be Proulx, and Rossmo, 2005). broken down into two components: the Additional elements which are search for a suitable victim and the method important to geographic profiling are of attack. The victim selection method is crime location, types, target backcloth, and categorized as hunter, poacher, troller, and offender hunting styles. Other factors to trapper. Crimes of a hunter are generally consider during the investigation are the confined to the offender’s city of residence location of arterial roads and highways, and the offender sets out from their presence of bus stops and rapid transit residence to search for victims in the area stations, physical and psychological within their awareness space. boundaries, zoning and land use, The victim attack method is neighborhood demographics, routine defined as raptor, stalker, and ambusher activities of victims and displacement (Rossmo, 2000). The raptor is (Rossmo, 1997). characterized by attacking almost immediately upon encountering their Movement and Distance victim. Whereas the stalker follows, watches their victim and waits for an As seen in Stea (1969), an individual’s opportune moment to attack. The attack, perception of distance is influences by murder, and victim release sites are thus several factors, including (1) relative strongly influences by the victim activity attractiveness of origins and destinations; space. Finally, the attack of the ambusher (2) number and types of barriers is committed someplace where the separating points; (3) familiarity with offender has a great deal of control, such routes; (4) actual physical distance; and as their residence or workplace (Rossmo). (5) attractiveness of routes (Rossmo, 2000). Murder and Distance Mental Maps As seen in Keppel and Weis (1993), they found, the more information known Mental maps are cognitive images of 2 familiar areas such as neighborhoods or serial murders have very defined cities formed from a distillation of the geographic areas of operation. They particular transactions a person has with conduct their killings within comfort zones his or her surroundings (Rossmo, 2000). which are often defined by an anchor Mental maps have an influence on crime point. Serial murderers will, at times, site selection because a target cannot be spiral their activities outside of their victimized unless an offender is first aware comfort zone, when their confidence has of it (Rossmo). grown through experience or to avoid detention. Very few serial murderers travel Awareness Spaces interstate to kill (FBI). Awareness spaces are defined as all the Case Studies locations about which a person has knowledge above a minimum level even Lundrigan and Canter (2001), examined without visiting some of them (Rossmo, the geographic distribution of the sites at 2000). which 126 US and 29 UK serial murderers disposed of their victim’s bodies. They Activity Spaces found the majority of the murderers operate within area that bore a strong Activity spaces are defined as the area relationship to their home. Also, it was within which most of a person’s activities found that rational choice and routine are carried out, within which the activity models of criminal behavior could individual comes most frequently into explain the spatial choices of serial contact with others and with the features murderers (Lundrigan and Canter). They of the environment (Rossmo, 2000). reported the median and average residence-to-crime distances for American Anchor Points serial murderers were 15 km (9.315 miles) and 40 km (24.82 miles), respectively As seen in Coucelis, Golledge, Gale and whereas the median and average Tobler; 1987, activity space are anchor residence-to-crime distances for UK serial points or bases, the most important places murders were 9 km (5.589 miles) and 18 in one’s spatial life (Rossmo, 2000). The km (11.178 miles) (Lundrigan and main anchor point for the vast majority of Canter). people it is their residence, but other bases In a study conducted by Snook, may exist such as a worksite or friend’s Cullen, Mokrus, and Harbort (2005), 53 home (Rossmo). German serial murderers were examined According to Canter (1994), for factors that influenced crime location offenders operate within the confines of choices. Results showed 63% of the their experiences, habits, awareness, and murderers lived within 10 km (6.21 miles) knowledge (Rossmo, 2000). Criminals of their crime locations (Snook et al.). select targets or victims from their Also, 78% of the victims were found awareness zones, and access them in terms within 20 km (12.42 miles) of the of criteria of suitability (gain or profit) and murderer’s residence and 84% were found risk (probability of being observed or within 30 km (18.63 miles) (Snook et al.). apprehended) (Ainsworth, 2001). Residence-to-crime distance was According to the FBI (2008), most negatively correlated with murderer age 3 and positively correlated with murderer