The making of an expert detective: the role of experience in English and Norwegian police officers’ investigative decision-making

Biased decision-making in criminal investigations can impede or arrest the progress of justice. Previous research has not systematically addressed the effects of professional experience on the quality of detectives’ decision-making. Using a quasi-experimental design, this study compared the quality of investigative decisions made by experienced detectives and novice police officers in two countries with markedly different models for the development of investigative expertise (England and Norway). Participants (N?=?124) were presented with two semi-fictitious cases and were asked to report all relevant investigative hypotheses and necessary investigative actions in each case. The quality of participants’ responses was gauged against a gold standard established by a panel of senior homicide experts. In the English sample, experienced detectives vastly outperformed novice police officers in the number of reported gold-standard investigative hypotheses and actions. In the Norwegian sample, however, experienced detectives did not perform any better than novices. We argue that English (vs. Norwegian) detectives may benefit more from professional experience due to their Professionalising Investigation Programme and a nationwide accreditation program, requiring them to engage in extensive standardized training, systematic evaluation and synchronized development. In contrast, Norway lacks such requirements. Methodological limitations and implications for police training and accreditation policies are discussed.     

Exploring the potential of stricter gun restrictions for people with serious mental illness to reduce homicide in the United States

This study explores the potential that current efforts to limit access to firearms for individuals with serious mental illness (SMI) have for reducing overall rates of murder by firearm in the United States. Official arrest, court and health records provided data on personal and offense characteristics of 95 individuals with SMI and 423 without, all of whom had been convicted of murder in the State of Indiana between 1990 and 2002. Bivariate analyses examined differences between the two groups and logistic regression models examined the relationship between SMI and offense characteristics. Compared to those without, a relatively small proportion of convicted murderers had a diagnosis indicating SMI. The presence of SMI was associated with reduced likelihood of targeting a stranger and was not associated with having multiple-victims or firearm use. Focusing on access to firearms exclusively by individuals with SMI will have little impact on multiple-victim or firearm-related homicides.     

Twenty years of femicide in Milan: A retrospective medicolegal analysis

Femicide constitutes a leading cause of premature deaths for women, yet it has been the subject of limited research until recently. Enhanced data collection and analysis on killings of women and girls are necessary to understand and address this unrelenting phenomenon. This study examines all cases of female homicide encountered at the Institute of Legal Medicine of Milan (Italy) spanning from 1999 to 2019; data from 2020/2021 were shown separately given the bias that the forced cohabitation and stay at home during the lockdowns of the SARS-CoV-2 pandemic may represent regarding violence against women and femicide. In this study, specific factors were considered, including the age and nationality of the victims, the place of recovery of the bodies, the victim’s relationship to the perpetrator and the injuries they suffered. As a result, 200 female killings were found among the over 15,000 autopsies and 535 homicides investigated at the Institute of Legal Medicine of Milan from 1999 to 2019, representing an average of 9.5 femicides yearly. The majority of victims were Italian (74%) and half were aged between 18 and 49 years old. The killings were overwhelmingly committed in the domestic setting (78.5%) by male perpetrators (at least 85%), related to the victims as intimate or ex-intimate partners and members of the family (73.5%). The homicides were mainly perpetrated with sharp (32%) or blunt instruments (21.5%), shooting (18.5%) and asphyxiation (16.5%). This study is part of a growing effort to enhance data collection and analysis on femicide. Studying and monitoring the rates of femicide (or “femicide watch”) will permit to better understand, reduce, and finally end femicide globally.     

An Empirical Study of Rape in the Context of Multiple Murder

In recent years, multiple homicide offending has received increased research attention from criminologists; however, there is mixed evidence about the role of rape toward the perpetration of multiple murder. Drawing on criminal career data from a nonprobability sample of 618 confined male homicide offenders selected from eight U.S. states, the current study examines the role of rape as a predictor of multiple homicide offending. Bivariate analyses indicated a significant association between rape and murder charges. Multivariate path regression models indicated that rape had a significant and robust association with multiple murder. This relationship withstood the confounding effects of kidnapping, prior prison confinement, and prior murder, rape, and kidnapping. These results provide evidence that rape potentially serves as a gateway to multiple murder for some serious offenders. Suggestions for future research are proffered.     

Persistence of Biological Traces at Inside Parts of a Firearm from a Case of Multiple Familial Homicide

Backspatter from wounds caused by contact shots against a biological target had before been shown to be propelled into firearms' barrels where they can persist and be retrieved from as relevant forensic evidence. Herein, that insight was applied to the investigation of a case of multiple familial homicide with a firearm. Samples of backspatter were collected from the firearm using DNA‐free swabs. DNA was extracted from the swabs, and 16 STR systems were PCR‐amplified to generate DNA profiles of all victims shot by the firearm. The quality of the resulting DNA profiles was sufficient to exclude the perpetrator as donor and to differentiate the three closely related victims thereby proving that all three victims had been shot by the same firearm from very close or contact distance. A key insight gained from this case was that not only a firearms' barrel inside but other inner surfaces may be charged with profilable DNA.     

The Effect of Previous Traumatic Injury on Homicide Risk

Research has reported that a strong risk factor for traumatic injury is having a previous injury (i.e., recidivism). To date, the only study examining the relationship between recidivism and homicide reported strong associations, but was limited by possible selection bias. The current matched case–control study utilized coroner's data from 2004 to 2008. Subjects were linked to trauma registry data to determine whether the person had a previous traumatic injury. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) for the association between homicide and recidivism. Homicide risk was increased for those having a previous traumatic injury (OR 1.81, 95% CI 1.09–2.99) or a previous intentional injury (OR 2.53, 95% CI 1.24–5.17). These results suggest an association between homicide and injury recidivism, and that trauma centers may be an effective setting for screening individuals for secondary prevention efforts of homicide through violence prevention programs.     

Evaluation of police recruit training involving psychology

Abstract

Claims have been made that critical thinking is a necessary skill for constructing accurate offender profiles. However, in studies purporting to demonstrate this, critical thinking ability amongst participants has never been adequately assessed, making it impossible to draw any valid conclusions about the importance of this skill for profiling. In order to empirically examine the relationship between critical thinking ability and profile accuracy, participants (n=36) in the current study completed a mock profiling exercise and the Watson–Glaser Critical Thinking Appraisal – Form S (WGCTA-S). Profile accuracy scores were calculated for each participant and correlated with his or her scores on the WGCTA-S. Although the majority of participants were found to be adequate critical thinkers, no significant relationship was found between critical thinking ability and profile accuracy. Potential explanations for this finding are discussed.     

A systematic review of the literature comparing male non-serial sexual killers and sexual aggressors: examining homogeneous and heterogeneous characteristics of these groups

ABSTRACT

This systematic review considers what is known about the characteristics of sexual killers and sexual aggressors. The aim was to identify which characteristics have consistently been shown to be similar (homogeneous) and which are different (heterogeneous) across these two groups. Ten studies, including approximately 300 sexual killers, were analysed. Only studies where the samples were directly compared and where sexual killers were male, predominantly non-serial and perpetrated against adult female victims were included. Results indicate that levels of loneliness and anger appear to be more prevalent in the sexual killer sample while mental health disorders, criminal history, family structure and history of sexual abuse as well as some crime scene behaviours seem to be similar across the two groups. The results of this review have also highlighted some methodological problems inherent to these types of studies and these issues are discussed from the perspective of improving research on these crimes.     

Understanding sexual homicide

Abstract

Sexual homicide is a crime that receives much media attention, but one that still has a relatively small research base compared to other crimes. Although the idea of someone deriving sexual gratification from or during the killing of another is an anathema to many, forensic professionals need to understand sexual homicide and the range of circumstances and motivations that lie behind it. This paper explores this complex crime: it illustrates the various definitions and labels used; it suggests that sexual homicide is rare and is committed by individuals who, although having troubled histories, may not differ from other offenders. Then, by examining the various legal and behavioural circumstances in which sexual homicide can occur, this paper illustrates the diversity of sexual homicide and presents it in a more understandable manner. Finally, the paper suggests that knowledge of this diversity is required both for investigative and clinical purposes.