Prediction of serial perpetrator residence: Part I—Induction of models utilising spatio-temporal routing functions and investigative information

This article presents a new framework for the geographic profiling problem which assesses and integrates the travel environment of road networks; beliefs and assumptions formed through the investigation process about the perpetrator; and information derived from the analysis of evidence. Each piece of information is evaluated in conjunction with functions which gather real-time travel information, including both time and distance of likely perpetrator travel, and is then used to update prior beliefs about the potential base of operation of the perpetrator. A novel approach was developed to generate geographic profiles given different amounts of information about the perpetrator: a centrographic strategy for when only the victim dump sites are known; a perpetrator trek strategy for instances where both victim encounter and dump sites are available; and a formal evidence-driven model which leverages and integrates available information and evidence relevant to the case for the development of a geographic profile. A follow-up article will evaluate these models through a comprehensive application to the Yorkshire Ripper investigation (see Part II).     

Choice of Weapon or Weapon of Choice? Examining the Interactions between Victim Characteristics in Single‐victim Male Sexual Homicide Offenders

As most studies report that the majority of sexual homicide offenders (SHOs) prefer to kill with their own hands, research has largely neglected to examine the choice of weapon by these offenders. The US Supplementary Homicide Reports show that although a large number of SHOs murder their victim using personal weapons (e.g. bare hands and manual or ligature strangulation), the majority use an alternative weapon (e.g. edged weapons, contact weapons, and firearms). The present study hypothesises that the choice of weapon is in part influenced by victim characteristics. To identify specific combinations and interactions between victim characteristics and the choice of a personal or edged weapon during the commission of a sexual homicide, a combination of exhaustive chi‐square automatic interaction detector and conjunctive analysis is used on a sample of 2,472 single‐victim male SHOs from a 36‐year period of Supplementary Homicide Report data (1976–2011). Findings show that SHOs choose their weapon according to some victim characteristics. Implications of the findings are discussed in light of police suspect prioritisation. Copyright © 2014 John Wiley & Sons, Ltd.     

Introduction to the special issue on Bayesian journey-to-crime modelling

In this special issue of the Journal of Investigative Psychology and Offender Profiling, we explore a Bayesian approach to journey-to-crime (JTC) estimation with an emphasis on the statistical models used. The approach conceptualises the probability that an offender lives at one location as the product of the probability distribution from a JTC estimate along with the probability distribution of other offenders who committed crimes in the same locations. The Bayesian approach is appropriate as the second part is conditional on the first part. The introduction gives the background behind the methodology and suggests how future improvements can be made by integrating new information. Finally, the papers in the special issue are introduced. Copyright © 2009 John Wiley & Sons, Ltd.     

The mathematics of geographic profiling

We begin by describing some of the mathematical foundations of the geographic profiling problem. We then present a new mathematical framework for the geographic profiling problem based on Bayesian statistical methods that makes explicit connections between assumptions on offender behaviour and the components of the mathematical model. It also can take into account local geographic features that either influence the selection of a crime site or influence the selection of an offender's anchor point. Copyright © 2009 John Wiley & Sons, Ltd.     

Target selection patterns in rape

Both theoretical and empirical studies of decision making in target selection have shown that this process is highly dependent on the physical environment. However, research specifically investigating decision making in sex offenders' target selection is scarce. The aims of the current study were to (1) identify target selection patterns in a mixed sample of 78 Canadian and Portuguese adult rapists, (2) investigate how geographical decision making influences target selection patterns, and (3) test the influence of the type of environment on target selection patterns. The results indicate that Canadian and Portuguese rapists exhibit different target selection patterns but that their geographical decision making is congruent and consistent with the environment within which they operate. Copyright © 2010 John Wiley & Sons, Ltd.     

Crime scene actions and offender characteristics in a sample of Finnish stranger rapes

The crime scene actions employed by offenders in stranger rapes were analysed in relation to offender characteristics. Data were drawn from an official police database and consisted of stranger rapes occurring in Finland between 1992 and 2001 (n = 100). The structure of dichotomous variables derived through a content analysis of crime scene actions and offender characteristics were analysed with non‐metric multidimensional scaling (MDS). The first analysis revealed three separate action themes, with thematic emphases on Hostility, Involvement or Theft. The MDS‐solution for offender characteristics suggested four themes: Conventional; Psychiatric/Elderly; Criminal/Violent; and Criminal/Property. Each case was assigned to one of the themes or as a hybrid in order to analyse the associations between action themes and characteristics. The only significant association was found between the action theme, Theft and characteristics theme Criminal/Property. The results are discussed in relation to previous research. Copyright © 2004 John Wiley & Sons, Ltd.     

Serial murderers' spatial decisions: factors that influence crime location choice

The outcome of German serial murderer spatial decision making was measured as the straight‐line distance (km) between murderer home locations and each crime location (i.e. body recovery location). Geographic and series development data, as well as information on age, intelligence, motive, marital status, employment status, and mode of transportation of 53 German serial murderers was collected from police and prosecution service files and judicial verdict records. Potential effects of the aforementioned factors on spatial decisions were assessed. Results showed that 63% of the murderers lived within 10 km of their crime locations. Home‐to‐crime distance was negatively correlated with murderer age and positively correlated with murderer IQ score. Results also showed that the mode of transportation used by murderers had an effect on their spatial decisions. Results are discussed in terms of understanding serial murderer spatial decision‐making and implications for police investigations. Copyright © 2005 John Wiley & Sons, Ltd.     

The Jack the Ripper murders: a modus operandi and signature analysis of the 1888–1891 Whitechapel murders

A number of females, commonly recognized as 11 victims, were murdered in separate events in Whitechapel, London between 1888 and 1891. An evaluation of the murders revealed that six of those murders were linked by a number of distinct, personal signature characteristics, including picquerism, overkill, incapacitation, domination and control, open and displayed, unusual body position, sexual degradation, mutilation, organ harvesting, specific areas of attack, preplanning and organization, and a combination of signature features. The signature characteristics observed in these infamous Jack the Ripper murders were compared to a 1981–1995 cohort of 3359 homicide cases from Washington State's HITS database. The analysis revealed that the signature displayed in six of the Whitechapel murders was extremely rare. There were only six records of female victims, one a prostitute, with probed, explored, or mutilated body cavities. There were only two cases, both females who were not prostitutes, where the body was left in an unusual position and body cavities were explored, probed, or mutilated. Copyright © 2005 John Wiley & Sons, Ltd.