Unknown Offender Research Articles

From Crime Scene Actions in Stranger Rape to Prediction of Rapist Type: Single‐Victim or Serial Rapist?

The differences in crime scene actions in cases of stranger rape committed by convicted offenders were examined between 31 single-victim rapists and 35 serial rapists. Data were collected from police files, court verdicts, psychiatric evaluations, and criminal records. Findings indicate that the serial rapists were more criminally sophisticated than the single-victim rapists, during their first and second rapes. The single-victim rapists were significantly more likely to engage in the interpersonal involvement behavior of kissing the victim, and to engage in pre-assault alcohol use, than the serial rapists. There was, however, no significant difference in physically violent or sexual behaviors. To investigate the possibility of predicting rapist type, logistic regression analyses were performed. Results indicate that three behaviors in conjunction, kissed victim, controlled victim, and offender drank alcohol before the offense, predicted whether an unknown offender is a single-victim or serial rapist with a classification accuracy of 80.4%. The findings have implications for the classification of stranger rapists in offender profiling.

Resolving the Offender “Profiling Equations” and the Emergence of an Investigative Psychology

Determining the characteristics of an unknown offender from details of a crime is at the heart of much crime fiction. Although it has roots in the inferences made by Sherlock Holmes, Sir Arthur Conan Doyle never provided empirical evidence for Holmes' inferences, or models of how such inferences can be made. Yet it ought to be possible to utilize psychological theories to derive inferences about offenders. This possibility has become a significant aspect of the new domain known as investigative psychology, which among other things seeks to establish what are called “profiling equations.” Although these are not equations in the literal, mathematical sense, they serve to summarize the search for consistent associations between aspects of a crime and features of the criminal that will be useful to investigations. Some progress has been made in modeling the process for establishing these links, elucidating consistencies in human actions often ignored in studies of individual differences.

A theoretical and practical test of geographical profiling with serial vehicle theft in a U.K. context

Geographical profiling is an investigative methodology sometimes employed by the police to predict the residence of an unknown offender from the locations of his/her crimes. The validity of geographical profiling, however, has not been fully explored for certain crime types. This study, therefore, presents a preliminary test of the potential for geographical profiling with a sample of 145 serial vehicle thieves from the U.K. The behavioural assumptions underlying geographical profiling (distance decay and domocentricity) are tested and a simple practical test of profiling using the spatial mean is presented. There is evidence for distance decay but not domocentricity among the spatial behaviour of car thieves from the U.K. A degree of success was achieved when applying the spatial mean on a case-by-case basis. The level of success varied, however, and neither series length in days nor number of crimes could account for the variation. The findings question previously held assumptions regarding geographical profiling and have potential theoretical and practical implications for the study and investigation of vehicle theft in the U.K.

Taking Stock of Accuracy in Criminal Profiling: The Theoretical Quandary for Investigative Psychology

ABSTRACT This article presents an overview of quasi-experimental research that has investigated the performance of individuals engaged in the forensic psychological technique commonly known as criminal profiling. Recent conflict in the literature is examined with the result that, consistent with earlier findings, empirical evidence is found to support the capabilities of expert profilers in decisively surpassing nonprofilers in accurately predicting the characteristics of an unknown offender. Observations are offered in conclusion on the broader ramifications of these findings for competing theoretical approaches to criminal profiling.

Constructing Bayesian networks for criminal profiling from limited data

The increased availability of information technologies has enabled law enforcement agencies to compile databases with detailed information about major felonies. Machine learning techniques can utilize these databases to produce decision-aid tools to support police investigations. This paper presents a methodology for obtaining a Bayesian network (BN) model of offender behavior from a database of cleared homicides. The BN can infer the characteristics of an unknown offender from the crime scene evidence, and help narrow the list of suspects in an unsolved homicide. Our research shows that 80% of offender characteristics are predicted correctly on average in new single-victim homicides, and when confidence levels are taken into account this accuracy increases to 95.6%.

Effectiveness of Applying a Bayesian Network to the Offender Profiling: Stochastic Inference of the Indoor-sex-offender’s Employment

Offender profiling is one of the tools of decision making for criminal investigation. It is a set of techniques to infer characteristics of an unknown offender, such as sex, age bracket, lifestyle, psychological feature, previous crime, inhabited area, from the information which is left at the crime scene. In this article, we proposed a tool of decision-making for criminal investigation from the perspective of prediction of an uncertain event by the use of a Bayesian Network (BN). BN is a probability model that describes causal structure of events as chain networks of conditional probability, and is capable to predict the possibility of uncertain events. To examine the validity of the constructed model, firstly, we divided previous offenders’ information of the indoor-sex-offence cases into a training data (9,859 cases) and validation data (50 cases). Secondly, we constructed a model from the training data by means of K2 and MDL (minimum description length) as search-algorithm and information criteria, respectively. Finally, the validity of the model was examined by the validation data as virtual cases. According to the model, 21 target variables (16 behavioral variables, 2 vehicle variables and 3 victim variables) linked the explanatory variable (employment) directly, and most of these variables related to the employment. The results of the model validity showed that the accuracy of predicting the employment increased 10% higher when the age bracket could be estimated from the testimony of the victim. The results indicated that the BN model of the offender profiling would be able to provide valuable information for decision making for crime investigation. To predict characteristics of an unknown offender more accurately, it is crucial to select more appropriate information criteria and develop the search-algorithm, as well as to construct the database from more accurate information.

MtDNA Investigations After Differential Lysis

In order to gain information regarding the ethnic origin of an unknown offender in a murder case it was necessary to sequence the HV1 and 2 regions of the mitochondrial DNA (mtDNA). The only evidentiary material that could be linked to the suspect was DNA, extracted from spermatozoa after differential lysis. The observed mtDNA sequences were identical to the sequences of the victim. Therefore, we had to check if this was a coincidence or the result of a technical limitation of the testing procedure. Subsequently, we performed a systematic study. In cases with complete separation of sperm and female cells it wasn't possible to obtain a mtDNA sequence for the sperm fraction. This phenomena is based on the loss of the sperm's flagellum and mid-piece during the first lysis step and a concomitant loss of the sperm's mitochondria. In our murder case, a minor carry-over of female cells to the sperm fraction was responsible for the sequencing result.

Believing is seeing III: perceptions of content in criminal psychological profiles.

This study explored Kocsis and Heller's findings concerning the relationship between one's belief and the perceived accuracy of a profile. The influence of types of information was also considered. A sample of 353 participants was used in the present experiment that gauged the perception of information contained in a profile. The results supported Kocsis and Heller's earlier findings with a positive relationship found between belief and perceived accuracy. The more an individual believes in profiling, the more likely he or she is to perceive a profile to be accurate. This relationship was most pronounced in participants' perceptions of information contained in a profile concerning an unknown offender's crime behavior and past history. The more an individual believes in profiling, the more information relating to these two factors is likely to be perceived. This relationship was not observed where information in the same profile involved physical features of the offender.

Conceptualizations of Forgiveness

The objectives of the survey were to examine the extent to which (1) laypeople agree with conceptualizations of forgiveness encountered in literature, notably that forgiveness supposes the replacement of negative emotions toward the offender by positive emotions, (2) forgiveness is a process that can only take place between an offended and an offender who is known to the offended, and (3) forgiveness is not a process that devalues the forgiven but a process that encourages him/her to behave better in the future. It was also aimed at examining the extent to which parents and children share the same conceptualizations about forgiveness. A total of 343 students participated in the study as well as their mothers and fathers. Four conceptualization factors were identified: Change of Heart, More-Than-Dyadic Process, Encourages Repentance, and Immoral Behavior. Only a minority of participants agreed with the idea that forgiving supposes regaining affection or sympathy toward the offender (23%), and with the idea that forgiveness can encourage repentance from the forgiven (33%). More participants, however, agreed with the ideas that the forgiver can be somebody in close relationship with the offended and that the forgiven can be an unknown offender or an abstract institution (46%). Very few participants (4%) agreed with the idea that forgiveness is immoral. Parents and their children tended to conceptualize forgiveness similarly.

Criminal psychological profiling: validities and abilities.

Criminal psychological profiling has attained unprecedented recognition despite little empirical evidence to support its validity and the absence of any thorough exposition of the skills involved with the technique. This article reports on the empirically derived conclusions of studies that sought to examine the accuracy and skill of various groups performing a profiling task. The conclusions provide some support for the contention that professional profilers can produce a more accurate prediction of an unknown offender in comparison to other studied groups. The results also give an indication of the type of skills required for proficient profiling.

Crime Scene Profiling in Premises Security Litigation

In premises security litigation, the issue often involves whether some absent security measures would have deterred the offender. A typology is presented, categorising offenders according to how motivated they are to commit the crime and to avoid capture. Especially when offenders are unknown, however, it is problematic to determine their motivation. Crime scene profilers maintain that they can infer personality characteristics of an unknown offender. The reliability and validity of crime scene profiling is reviewed, and some suggestions are made as to ways that profilers can be helpful, such as estimating the intelligence level and criminal experience of the offender.

The child molester empathy measure: description and examination of its reliability and validity.

The aim of the two studies presented here was to produce and refine a measure of victim empathy for the assessment of child molesters. In the first study, 61 nonfamilial child molesters completed the Child Molester Empathy Measure (CMEM), a questionnaire designed specifically for this study. The measure assessed empathy in three contexts: (a) toward a child who was in a motor vehicle accident and was disfigured, (b) toward a child who had been sexually molested by an unknown assailant over a period of time, and (c) toward the offender's own victim(s). Results indicated that the measure was both internally reliable and produced stable responses over time. The results also revealed a relative deficit in empathy toward the offender's own victim(s). The goal of the second study was to replicate the data obtained in the first study and compare child molesters' responses with the responses of a group of nonoffenders. Twenty-nine child molesters and 36 community males (nonoffenders) completed the questionnaire. This study also confirmed the internal reliability and test-retest reliability of the CMEM. The discriminant validity of the measure was supported by the child molesters' demonstrated relative deficiency in empathy toward an unknown offender's victim of sexual abuse. However, the child molesters displayed equal empathy toward the accident victim relative to nonoffenders. Additionally, the child molesters displayed significantly less empathy toward their own victims than toward the general sexual abuse victim. The results are discussed in terms of their theoretical and practical implications.

Homosexual homicides

This report describes four cases of male homosexual homicide committed in Split County, Croatia, in 1991 and 1995. The homosexual orientation of the victims was determined by police investigation. Three middle-aged to elderly person were killed by an unknown offender or offenders, in very similar ways within a few months of end other in 1991. The bodies were found in their houses with multiple blunt force injuries to the head. One victim also had marks of manual strangulation, and was choked with a handkerchief which had been put in his mouth. The last victim was a 45-year-old man, found in the bathroom with 33 stab wounds, mostly in the neck and back, and with two shots in the head from an underwater gun. He was killed by two adolescent males at the beginning of sexual intercourse. The presented cases show a high level of violence with multiple injuries may be associated with male homosexual homicide.