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Case linkage: Offender modus operandi and signature
... There is some disagreement on whether crime linkage should be used as evidence in the courts at all. Some authors (e.g., Cooley, 2012;Turvey & Freeman, 2012) argue that it should not, stating that current crime linkage practices (in the United States) are too ambiguous to hold up to standards of admissibility. On the other hand, Labuschagne (2006; argues that crime linkage can be useful as evidence in court, giving examples of cases from South Africa where behavioral linkage evidence has been admitted by the court. ...
... Crime linkage is one of the offender profiling techniques used in the forensic context (Labuschagne, 2012;Turvey & Freeman, 2012). In our review of legal cases, the crime linkage expert typically offered an opinion on whether the same person had committed two or more crimes; that is, if the cases were linked. ...
... For obvious reasons, there is a risk of confirmation bias distorting the ViCAP search, which the court noted and took into consideration when declining the admission of it into evidence. It is also of critical importance to objectively evaluate the case as a whole, looking at both similarities and dissimilarities (as pointed out by the court's opinion, and Turvey & Freeman, 2012) and, ideally provide a statistical measure of rarity for said similarities and dissimilarities, in order to minimize the risk of confirmation bias. ...
The increasing portrayal of forensic investigative techniques in the popular media—CSI, for example, has resulted in criminals becoming "forensically aware" and more careful about leaving behind physical evidence at a crime scene. This presents law enforcement with a significant problem: how can they detect serial offenders if they cannot rely on physical forensic evidence? One solution comes from psychology. A growing body of research has amassed in the area of behavioral consistency and the detection of serial offenders. A number of innovations are taking place in the field that have important implications for the practice of crime linkage and its use by police and the courts. Crime Linkage: Theory, Research, and Practice assembles this research and discusses its practical use.
The book represents a collaboration of researchers and practitioners from across the globe who are recognized as experts in the area of behavioral consistency and detection of serial offenders. They provide a comprehensive and informative text on the psychological and criminological theories underpinning crime linkage, how it is used in practice, the challenges practitioners face, and current innovations that will shape the future of crime linkage research and practice.
... Critical infrastructures intended to provide civil transport have public spaces that make them especially vulnerable to crime. Any person who attempts to commit a criminal act display a modus operandi (specific behaviors) to protect his/her identity, achieve his/her goals and ensure a possible escape when needed (Turvey and Freeman 2012). Within the processes of self-regulation, people who are going to commit an illegal activity voluntarily initiate strategic behaviors they consider necessary to achieve the desired goal (completion of the crime) and avoid the unwanted outcomes (detection and possible punishment) (Carver and Scheier 2012). ...
... The detection capabilities of the behaviors prior to the crime event were also tested and, hence, appeared immediately before the criminal act (Baettig et al. 2011;Troscianko et al. 2004). Therefore, all the actions displayed by a person with the intention to commit a crime can be considered as part of the modus operandi that enables the perpetrator to protect himself/herself from being discovered and succeeding in his/ her action (Turvey and Freeman 2012). Furthermore, other behaviors not subject to voluntary control can also be activated, such as nervousness (restlessness not justified by other causes such as searching for a person or rushing to embark on a flight) and excessive sweating (not justified, for example, due to a medical condition or inappropriate clothing). ...
Airports are critical infrastructures that require special protection. Public spaces are considered vulnerable areas and a possible target for general crime as well as terrorism. Because of the latest terrorist attacks which targeted vulnerable areas in airports, it is essential to test proactive methods capable of helping to detect potential threats. In this context, there are also other illicit activities closely related to civil air transport, which must also be addressed. First, we propose a theoretical framework to explain the presence and detection of anomalous behaviors. Therefore, in this research, we start by analyzing the behavior of airport users (N = 352) in terms of “patterns of movement,” “patterns of communication,” indicators activated by the autonomic nervous system, and object adaptors. The results show significant differences in both movement and communication patterns between those who commit illegal acts and those who do not. No significant differences were found related to indicators coming from the autonomous nervous system or the object adaptors. Six significant behaviors account for the 49% of the variance in those who commit illegal activities. Three significant behaviors account for the 19% of the variance in those who possess background records.
... Based on the above assumptions, behavioral similarity has been successfully used to detect serial crimes, which can be applied not only to serious crimes, but also to large-scale crimes, such as theft and robbery and so on [6]. Crime linkage(CL) refers to the identification of crimes committed by the same suspect based on behavioral similarity [3], also called linkage analysis, case linkage, crime linkage [7]. It has been applied to many types of crime, such as serial sexual offenses [8,9], serial robbery [10,11], serial burglary [12,13] and so on. ...
Crime linkage is a challenging task in crime analysis, which is to find serial crimes committed by the same offenders. It can be regarded as a binary classification task detecting serial case pairs. However, most case pairs in the real world are nonserial, so there is a serious class imbalance in the crime linkage. In this paper, we propose a novel random forest based on the information granule. The approach doesn’t resample the minority class or the majority class but concentrates on indistinguishable case pairs at the classification boundary. The information granule is used to identify case pairs that are difficult to distinguish in the dataset and constructs a nearly balanced dataset in the uncertainty region to deal with the imbalanced problem. In the proposed approach, random trees come from the original dataset and the above mentioned nearly balanced dataset. A real-world robbery dataset and some public imbalanced datasets are employed to measure the performance of the approach. The results show that the proposed approach is effective in dealing with class imbalances, and it can be extended to combine with other methods solving class imbalances.
Abstract
This paper reviews the crime linkage literature to identify how data were pre-processed for analysis, methods used to predict linkage status/series membership, and methods used to assess the accuracy of linkage predictions. Thirteen databases were searched, with 77 papers meeting the inclusion/exclusion criteria. Methods used to pre-process data were human judgement, similarity metrics (including machine learning approaches), spatial and temporal measures, and Mokken Scaling. Jaccard's coefficient and other measures of similarity (e.g., temporal proximity, inter-crime distance, similarity vectors) are the most common ways of pre-processing data. Methods for predicting linkage status were varied and included human (expert) judgement, logistic regression, multi-dimensional scaling, discriminant function analysis, principal component analysis and multiple correspondence analysis, Bayesian methods, fuzzy logic, and iterative classification trees. A common method used to assess linkage-prediction accuracy was to calculate the hit rate, although position on a ranked list was also used, and receiver operating characteristic (ROC) analysis has emerged as a popular method of assessing accuracy.
The article has been published open access and is free to download from https://www.sciencedirect.com/science/article/pii/S1359178924001046
A presente dissertação surge no âmbito do curso de mestrado em Ciências Policiais, área de especialização em Criminologia e Investigação Criminal do Instituto Superior de Ciências Policiais e Segurança Interna.
O profiling criminal, associado à disciplina da Psicologia Forense, é uma técnica auxiliar na investigação criminal bastante utilizada no desbloqueamento de crimes considerados mais graves como homicídios, abusos sexuais a crianças e adolescentes, sequestros e situações associadas a incêndios. Sendo uma estratégia adotada por um grande número de países estrangeiros, é nosso objetivo analisar e estudar (ainda que de forma exploratória) a validade e a utilidade da mesma bem como as suas limitações, não só num contexto geral como na aplicação à realidade portuguesa. Será abordado, também, o enquadramento histórico do profiling, a sua aplicação em diversos casos na esfera criminal, matérias como o crime linkage, a vitimologia e os riscos que poderão estar associados à utilização desta técnica.
Palavras-chave: Profiling Criminal. Investigação Criminal. Vitimologia. Psicologia criminal. Riscos associados. Validade e relevância.
This dissertation comes within the scope of the Master's course in Police Sciences, specialization in Criminology and Criminal Investigation, of the Higher Institute of Police Sciences and Internal Security.
Criminal profiling, associated with the discipline of Forensic Psychology, is an auxiliary technique in criminal investigation widely used in unblocking crimes considered more serious such as homicides, sexual abuse of children and adolescents, kidnappings and situations associated with fires. As a strategy adopted by a large number of foreign countries, our goal is to analyze and study (even if in an exploratory way) its validity and usefulness, as well as its limitations, not only in a general context but also in its application to the portuguese reality. It will also address the historical background of profiling, its application in various cases in the criminal sphere, matters such as crime linkage, victimology and the risks that may be associated with the use of this technique.
Keywords: Criminal Profiling. Criminal Investigation. Victimology. Criminal Psychology. Associated Risks. Validity and Relevance.
A critical issue in genealogy is proving genealogical identity. Failure to do so often results in generational linkages and entire pedigrees built on fantasy. Correctly separating different individuals and combining records related to the same individual require careful analysis and consideration of evidence using personal qualities, relations, events, and objects such as places of residence or employment, key dates, occupation, religion, and physical characteristics. This article explores two behavioral identifiers—criminal modus operandi and psychoanalysis. To illustrate the argument that they can serve an important role in establishing identity, it examines the case of John Hatton, a teenaged London thief who was transported to America in 1726. Using a trial transcript and other evidence, the paper argues that criminal modus operandi and psychoanalysis can, where adequate evidence survives, be used to adduce genealogical identity, thus enabling one to combine evidence recorded at different times and across two continents.
Purpose. Through an examination of serial rape data, the current article presents arguments supporting the use of receiver operating characteristic (ROC) analysis over traditional methods in addressing challenges that arise when attempting to link serial crimes. Primarily, these arguments centre on the fact that traditional linking methods do not take into account how linking accuracy will vary as a function of the threshold used for determining when two crimes are similar enough to be considered linked.
Methods. Considered for analysis were 27 crime scene behaviours exhibited in 126 rapes, which were committed by 42 perpetrators. Similarity scores were derived for every possible crime pair in the sample. These measures of similarity were then subjected to ROC analysis in order to (1) determine threshold‐independent measures of linking accuracy and (2) set appropriate decision thresholds for linking purposes.
Results. By providing a measure of linking accuracy that is not biased by threshold placement, the analysis confirmed that it is possible to link crimes at a level that significantly exceeds chance ( AUC = .75). The use of ROC analysis also allowed for the identification of decision thresholds that resulted in the desired balance between various linking outcomes (e.g. hits and false alarms).
Conclusions. ROC analysis is exclusive in its ability to circumvent the limitations of threshold‐specific results yielded from traditional approaches to linkage analysis. Moreover, results of the current analysis provide a basis for challenging common assumptions underlying the linking task.
Three female patrons of singles bars were murdered in separate events in Bellevue, Washington in 1990 within sixty-seven days of each other. An evaluation of those murders revealed that all the murders were linked by a distinct personal "signature" or "calling card" left by the killer. As reported in the literature, the modus operandi of a killer frequently changes from one murder to the next and is different from the killer's signature, which is a permanent psychological imprint at each scene. The murder cases reported here demonstrate an elaborate signature of one killer who engaged in a rare personalization of his necrophilic fantasies by posing, openly displaying, and sexually inserting foreign objects into each one of three victims' bodies.