Diffusion in Homicide: Exploring a General Method for Detecting Spatial Diffusion Processes

This article proposes a new method for examining dynamic changes in thespatial distribution of a phenomenon. Recently introduced exploratoryspatial data analysis (ESDA) techniques provide social scientists with anew set of tools for distinguishing between random and nonrandom spatialpatterns of events (Anselin, 1998). Existing ESDA measures, however, arestatic and do not permit comparisons of distributions of events in the samespace but across different time periods. One ESDA method—the Moranscatterplot—has special heuristic value because it visually displayslocal spatial relationships between each spatial unit and its neighbors. Weextend this static cross-sectional view of the spatial distribution ofevents to consider dynamic features of changes over time in spatialdependencies. The method distinguishes between contagious diffusion betweenadjoining units and hierarchical diffusion that spreads broadly throughcommonly shared influences. We apply the method to homicide data, lookingfor evidence of spatial diffusion of youth-gang homicides acrossneighborhoods in a city. Contagious diffusion between neighboring censustracts is evident only during the year of peak growth in total homicides,when high local rates of youth-gang homicides are followed by significantincreases in neighboring youth- nongang rates. This pattern is consistentwith a spread of homicides from gang youth to nongang youth. Otherwise, theincreases in both youth-gang and youth- nongang homicides generally occursimultaneously in nonneighboring tracts.     

A Comparative Study of Children and Adult Homicide Rates in the USA and the Major Western Countries 1974–1999: Grounds for Concern?

The aim of this study is to examine the changing patterns of child homicide in the USA and the other 9 major Western countries between 1974 and 1999. On the basis of standardized WHO mortality data, 5-year mean rates of Baby (<1 year), Infant (1–4), Child (5–14), and General Population Rates for Homicide (GPRH) were analyzed for 1974–78 and 1995–99 for the USA and major Western countries. The analysis provided ratios of change for children's homicide between 1974 and 1999 and ratio of ratios between adult' and children's homicide. Over the period USA male Baby homicide rose by 78% and Females 44% with a combined rise in All Children [0–14] homicides of 45%, within the context of a declining adult GPRH. In the 1970s, 3 major Western countries had either higher or similar children's homicide rates to the USA, but by the late 1990s none did. Moreover, between 1974 and 1999, the USA had the biggest rise in Baby (<1) and All Children's deaths, and only France had substantial increases, whereas Baby homicide rates fell significantly in 6 other countries. The findings indicate a worrying deterioration in U.S. child homicides. Possible links with child abuse and explanations for the results are briefly discussed. Urgent case-specific research is required to determine the cause/s for and how to reverse the worsening child homicide situation in the USA.     

Female Sexual Homicide Offenders: A Descriptive and Comparative Study

Research on female sexual homicide has been very scarce. In Europe, it has rarely been examined, and in Scotland, it has never previously been studied. This exploratory study aims to examine the characteristics of sexual homicides involving female offenders between 1990 and 2015 in Scotland. Using data from the Scottish Homicide Database between 1990 and 2015, female sexual homicides (n = 7) were compared to nonsexual homicides committed by females (n = 106) and to sexual homicides committed by men (n = 89) using Fisher's exact tests. The findings show that although female sexual homicide offenders are similar to both female nonsexual homicide offenders and male sexual homicide offenders in certain aspects, there are important differences that distinguish sexual homicides involving female offenders from both groups. Female sexual homicide offenders can arguably be seen as a distinct group of offenders, with specific characteristics and specific needs.     

COMMUNITIES,STREET GUNS AND HOMICIDE TRAJECTORIES IN CHICAGO, 1980–1995: MERGING METHODS FOR EXAMINING HOMICIDE TRENDS ACROSS SPACE AND TIME*

We merge Exploratory Spatial Data Analysis (ESDA) and a semi‐parametric, group‐based trajectory procedure (TRAJ) to classify communities in Chicago by violence trajectories across space. Total, street gun and other weapon homicide trajectories are identified across 831 census tracts between 1980 and 1995. We find evidence consistent with a weapon substitution effect in violent neighborhoods that are proximate to one another, a defensive diffusion effect of exclusively street gun‐specific homicide increases in neighborhoods bordering the most violent areas, and a spatial decay effect of temporal homicide trends in which the most violent areas are buffered from the least violent by places experiencing mid‐range levels of lethal violence over time. In merging these two methods of data analysis, we provide a more efficient way to describe both spatial and temporal trends and make significant advances in furthering applications of space‐time methodologies.     

Can Cohort Replacement Explain Changes in the Relationship Between Age and Homicide Offending?

This paper focuses on shifts in the age distribution of homicide offending in the United States. This distribution remained remarkably stable with small but significant changes over a long period of time. Then between 1985 and 1990 the rates of homicide offending doubled for 15-to-19 year olds and increased nearly 40% for 20-to-24 year olds, while the homicide offending rates decreased for those over 30. In addition to this “epidemic of youth homicide,” which lasted through the mid-1990s, there have been systematic changes in the age distribution of homicide in the United States associated with cohort replacement over the past 40 years. We introduce an estimable function approach for estimating the effects of age, period, and cohort. The method allows us to assess simultaneously the impacts of periods and cohorts on the age distribution of homicide offending. We find that although the age curve remains relatively stable, there are shifts in it associated systematically with cohort replacement. Cohort replacement accounts for nearly half of the upturn in youth homicides during the epidemic of youth homicides, but a significant fraction of that upturn is not associated with cohort replacement.

A Move Toward Specificity: Examining Urban Disadvantage and Race-and Relationship-Specific Homicide Rates

The purpose of this research is to estimate the differential impact of structural conditions on race- and relationship-specific homicide rates for U.S. cities in 1990. The structural conditions commonly employed in race-specific homicide research are examined, such as job accessibility, economic deprivation, racial segregation, and racial inequality. Furthermore, four relationship categories of homicide—acquaintance, family, stranger, and intimate—are disaggregated by racial group. The detailed relationship-specific homicide rates are compared to a baseline homicide rate to determine whether structural factors associated with urban disadvantage similarly influence homicide rates across relationship types. The results indicate that differences emerge in the impact of structural conditions on homicides disaggregated by race- and relationship-specific categories. Theoretical explanations consistent with criminology and race-relations literature are discussed, as well as the potential benefits and implications for studies that pursue more meaningful and detailed classifications in homicide offending.     

The effects of marital status and social isolation on adult male homicides in the United States: Evidence from the National Longitudinal Mortality Study

With data from the 1979–1985 Longitudinal Mortality Study, we examine the effects of marital status and social isolation on adult male homicide (ICD-9 Codes E960-E978). Cox proportional hazards models were fitted to a 1979–1981 population cohort of approximately 200,000 adult men and their mortality experiences were followed until 1984–1985. Multivariate hazards regression analysis showed that marital status and social isolation are associated with significantly higher risks of homicide victimization. Controlling for age and other socioeconomic covariates, single persons were 1.9 times, and divorced, separated or widowed persons were 1.7 times, more likely to die from homicide than married persons. Socially isolated persons were 1.6 times more likely to become homicide victims. Other adult males with increased risk of homicide victimization were African Americans and those who lived in the inner city.     

Facilitating Violence: A Comparison of Gang-Motivated, Gang-Affiliated, and Nongang Youth Homicides

It is well established that gangs facilitate violent offending by members,but the mechanisms by which that facilitation occurs remain unclear. Gangsmay promote violence indirectly by facilitating members' access to riskysituations such as drug markets or directly through gang functions such asturf defense. We explore alternative modes of facilitation in a comparisonof gang-affiliated homicides (which involve gang members but do not resultfrom gang activity), gang-motivated homicides (which result from gangactivity), and nongang youth homicides in St. Louis. We find importantdifferences as well as similarities in the time trends and eventcharacteristic of the two types of gang homicide; in key respects thegang-affiliated homicides more closely resemble the nongang events. Thegang-motivated events exhibit a somewhat distinctive spatial patterning,as might be expected from their connection to turf conflicts. However, allthree homicide types are highly concentrated in racially isolated,disadvantaged neighborhoods, which remain the fundamental socialfacilitators of both gang and nongang violence.     

Homicide Rates in Lithuania

Homicide rate in Lithuania between 2004 and 2013 decreased and reached an average of 6.7 per 100,000 people in 2013. The data regarding forensic autopsies of intentional homicide victims were obtained from the State Forensic Medicine Service. Spearman's correlation test was used to assess trends in the homicide rates. A significant correlation was observed between homicide distribution and the following variables: Lithuania's gross domestic product (r = ?0.85, p = 0.003), the number of alcohol intoxication cases of victims (r = 0.97, p < 0.05). After regression model adjustments, these variables remained significantly associated with the homicide distribution (p < 0.05). 73% of victims were men, with a mean age of 45.5 ± 15. Alcohol intoxication was present in 58% of victims. 66% of homicides were carried out indoors, 57% in urban area. The presented findings help decide which prevention programs may be the most effective in homicide rate reduction.     

Spatial patterns of homicide and political legitimacy in Europe*

Political legitimacy, or a state's “right to rule,” has been a concern for philosophers, political scientists, and sociologists for centuries. This paper examines the relationship between European states' level of political legitimacy and violence, as represented by their homicide rate. It is theorized that political illegitimacy affects homicide through deteriorating social institutions of control, violating the rules of reciprocity between the state and citizens, and/or creating an environment of “virtual statelessness” that encourages methods of “self-help.” Focusing on the modernized societies of Europe, where legitimacy may be more important to maintaining order, the present study reveals two important findings: political legitimate states have significantly lower levels of homicide, and high and low homicide rates in Europe are significantly clustered among post-Soviet states (high) and Western Europe (low).     

Homicide clearance in Sweden 1990–2013 with special reference to firearm-perpetrated homicides

Studies on homicide clearance in the Scandinavian context are very rare. In this article, we explore the homicide clearance rate in Sweden with special reference to firearm-perpetrated cases. The study is based on homicide research data collected by the Swedish National Council for Crime Prevention, comprising all 2160 homicides known to the Swedish authorities during the period 1990–2013. The annual clearance rate varied between 74 and 90%, with an overall minor decrease since the 1990s. However, there has been a considerable decrease in the clearance rate for firearm-perpetrated homicides. It can be concluded that this decrease is due to a shift in the characteristics of firearm-perpetrated offences, with homicides committed in public places against criminally active male victims having become more frequent. This finding is generally consistent with theories which argue that homicide clearance rates are predominantly affected by case-specific, non-discretional factors beyond the control of the police. The practical implications of the study are that investigative efforts should be more intense in cases where a male has been shot in a public place, and that homicides related to criminal milieus should be investigated by specialized units.     

The Unusual Victim: Understanding the Specific Crime Processes and Motivations for Elderly Sexual Homicide

Sexual homicides involving elderly victims are rare and unusual crimes, and research specifically focusing on these homicides is almost inexistent. The current study investigates the crime commission process as well as the motivations underlying elderly sexual homicides. The sample comes from the Sexual Homicide International Database (SHIelD) including sexual homicide cases from Canada and France. A total of 56 cases involving victims aged 65 years or more were compared with 513 cases involving victims aged between 16 and 45 years old. Bivariate analyses and two-step cluster analysis are performed. Findings show major differences in the crime commission process of the two groups of offenders. We also identified a four-cluster typology of elderly sexual homicide offenders based on their motivations (sexual, robber, sadistic, experimental). Although sexual homicides involving elderly victims are rare, these crimes are different, presenting specificities and should be studied as a group on its own.     

Families of Homicide Victims: Service Utilization Patterns of Extra- and Intrafamilial Homicide Survivors

Homicides precipitate numerous problems for victims' families that can be eased, in part, by counseling, case management, and court advocacy services. Guided by a crisis theory framework, the records of 112 homicide victims' family members (or survivors) served by a public victims assistance agency were examined to discern typical service utilization patterns and differences for survivors of intrafamilial homicides (i.e., cases in which the perpetrator was a family member of the victim). Results indicated that survivors of intrafamilial homicides utilized services during the initial 8-week crisis period following the homicide more than other survivors, yet used services less during the subsequent 8-week period. The findings substantiated the application of crisis theory to studying the experiences of survivors and underscored the importance of considering survivors' familial relationships to perpetrators in the provision of services.     

Examining Space–Time Interaction in City-Level Homicide Data: Crack Markets and the Diffusion of Guns Among Youth

This paper examines the linkage between crack market activity and gunhomicide suggested by Blumstein (1995), who argues that the arrival ofcrack stimulated an increased availability of guns among juveniles. Thisgreater availability of guns, the argument continues, is responsible for thesharp upswing in juvenile homicide experienced in the United States in themid-1980s. Using city-level data on crack arrests and gun-related juvenilehomicide, we fit a change-point version of the Bass (1969) model ofinnovation diffusion. We find that, in most large American cities, thediffusion process for crack cocaine experienced an onset of dramatic growththat was followed by a similar, slightly slower growth in gun homicidescommitted by juveniles. We further use cluster analysis to find that thespatial patterning of the two processes is similar, starting on the East andWest Coasts and working their way toward other regions of the nation. Gunuse in homicide among slightly older offenders (ages 18–24) alsoexperienced a change at roughly the same time as the juveniles, but the rateof diffusion was considerably milder than for the younger group; offendersages 25 or older generally show no growth in gun-related homicide whatsoever. In addition, there is no detectable surge in juvenile nongun homicide activity. Based on these findings, we conclude that the crack cocaine markets–gun availability linkage is highly plausible, and we suggest directions for future research in clarifying the dynamics of the late-1980s surge in juvenile homicide.     

Sharp Force Homicide in Denmark 1992–2016

Sharp force trauma is a common homicide method. The weapon is typically a knife, which is easily accessible and does not require special skills. We have analyzed all 471 sharp force homicides in Denmark during 1992–2016 with special focus on aspects that are relevant to forensic pathologists, including the distribution of wounds and organ injuries. Most homicides were committed inside with a kitchen knife. The front left thorax was the most common area to be affected by sharp force trauma. In 18.9% of the victims, there was only one sharp injury, the majority on the thorax. The most common trajectory for stab wounds was directly posterior with no deviation to the sides or up/down followed by directly anterior. The heart (including pericardium) and lungs (including hemo- and pneumothorax) had injuries in more than 75% of the victims. 67% of victims were males. Female victims had more sharp force injuries and defense wounds than male victims. Most females were killed in domestic homicides (73.7%), most commonly in partner killings (56.4%). In contrast, many male victims were killed in a setting of nightlife/intoxication (34.0%) most by a friend/acquaintance delivering a few stab wounds. The results clearly show strong sex differences in both victims and offenders. This could be useful for shaping policies and public opinion, and as a route for understanding the developments in interpersonal violence. In the narrow setting of death investigation, our results will provide an evidence-based approach to understanding the injury patterns in sharp force homicide.     

Extent, trends, and perpetrators of prostitution-related homicide in the United States

Prostitute women have the highest homicide victimization rate of any set of women ever studied. We analyzed nine diverse homicide data sets to examine the extent, trends, and perpetrators of prostitution-related homicide in the United States. Most data sources substantially under-ascertained prostitute homicides. As estimated from a conservative capture-recapture analysis, 2.7% of female homicide victims in the United States between 1982 and 2000 were prostitutes. Frequencies of recorded prostitute and client homicides increased substantially in the late 1980s and early 1990s; nearly all of the few observed pimp homicides occurred before the late 1980s. These trends may be linked to the rise of crack cocaine use. Prostitutes were killed primarily by clients, clients were killed mainly by prostitutes, and pimps were killed predominantly by pimps. Another conservative estimate suggests that serial killers accounted for 35% of prostitute homicides. Proactive surveillance of, and evidence collection from, clients and prostitutes might enhance the investigation of prostitution-related homicide.     

Body Transportation after Homicides: Offender and Offense Characteristics

Body transportation is defined as moving the body of the victim from the scene of a homicide to another location. We analyzed data on 513 South Korean homicide cases with convictions to compare 104 homicides involving the transportation of victims’ bodies with 409 homicides that did not. Offenders who transported their victims’ bodies were significantly younger and more likely to be related to the victims and were less likely to use sharp instruments and more likely to use blunt instruments or strangle the victims than offenders who did not. Victims of homicide involving body transportation were more likely to suffer injuries to the neck and head and less likely to suffer injuries to the torso. Finally, offenders who transported victims’ bodies were more likely to have planned the offense and destroyed evidence. The present findings have practical implications for police investigations.     

The Death of Freddie Gray and Its Impact on Homicides in Baltimore and Maryland

This study evaluated the impact that Freddie Gray’s death on April, 19, 2015, had on homicides within Baltimore, Prince George’s County, and the rest of Maryland. The numbers of these deaths were compared in the 2 years prior and after his death. The average number of homicide per month in Baltimore and Prince George’s County, but not the rest of Maryland, showed a statistically significant increase in the 2 years after his death, with a sudden spike in homicides in Baltimore immediately following his death. Spatial density (“heat”) maps of homicides showed an increase in clustering of deaths after Freddie Gray’s demise in portions of Baltimore, particularly near his arrest site. Hot spot maps showed a massive expansion of statistically significant clusters of homicides in areas of West and East Baltimore after his death. An emerging hot spot analysis revealed consecutive hot spots in large areas of West Baltimore with new hot spots prominent along the southern edge of this area. A review of the history of Baltimore, as well as discussions with Baltimore homicide detectives, revealed that prior socioeconomic and political trends likely primed Baltimore for the protests and violence that occurred after Freddie Gray’s death. It is probable that a perceived “overcharging” of officers involved in his death by the State’s Attorney resulted in a “pullback” from policing that directly led to increased homicides in Baltimore.     

Differences between Homicides Committed by Lone and Multiple Offenders in Korea

The aim of this study was to differentiate between homicides committed by multiple offenders and homicides committed by lone offenders. Using data on homicide incidents that occurred in South Korea between 1985 and 2008, we compared 134 homicides committed by multiple offenders, with 369 homicides committed by lone offenders. A greater proportion of homicides committed by multiple offenders involved injuries to the victim's head compared to homicides by lone offenders. Homicides committed by multiple offenders were more likely to involve blunt instruments and ligatures, whereas homicides by lone offenders were more likely to involve sharp instruments. In addition, a majority of the homicides committed by multiple offenders were planned. The results of this study have practical implications for homicide investigations, as well as theoretical implications for homicide research on the difference in offense behaviors based on the number of offenders.