Characteristics of School-Associated Youth Homicides — United States, 1994–2018

Kristin M. Holland, PhD; Jeffrey E. Hall, PhD; Jing Wang, MD; Elizabeth M. Gaylor, MPH; Linda L. Johnson; Daniel Shelby; Thomas R. Simon, PhD; School-Associated Violent Deaths Study Group

Disclosures

Morbidity and Mortality Weekly Report. 2019;68(3):53-60. 

In This Article

Abstract and Introduction

Introduction

To understand trends and characteristics in school-associated homicides involving youths, data from CDC's School-Associated Violent Death Surveillance System were analyzed for 393 single-victim incidents that occurred during July 1994–June 2016 and 38 multiple-victim incidents (resulting in 121 youth homicides) during July 1994–June 2018. School-associated homicides consistently represent <2% of all youth homicides in the United States.[1,2] The overall 22-year trend for single-victim homicide rates did not change significantly. However, multiple-victim incidence rates increased significantly from July 2009 to June 2018. Many school-associated homicides, particularly single-victim incidents, are similar to youth homicides unrelated to schools, often involving male, racial/ethnic minority youth victims, and occurring in urban settings. The majority of both single-victim (62.8%) and multiple-victim (95.0%) homicides were from a firearm-related injury. A comprehensive approach to violence prevention is needed to reduce risk for violence on and off school grounds.

The School-Associated Violent Death Surveillance System tracks lethal violence in school settings, providing a census of violent deaths (i.e., homicides, suicides, and legal intervention deaths) in school environments. Incidents are identified through a systematic media scan of computerized newspaper and broadcast media databases via LexisNexis (https://www.lexisnexis.com/) using keywords such as "shooting, death, violent, strangulation, beating, attack, stabbing, and died" combined with phrases including "primary or secondary or elementary or junior or high or middle or during or after or grounds or property or playground." Cases include incidents where a fatality occurred 1) on a functioning public or private primary or secondary school campus in the United States; 2) while the victim was on the way to or from regular sessions at such a school; or 3) while the victim was attending or traveling to or from an official school-sponsored event. This study analyzed data for single-victim homicides during July 1994–June 2016 and multiple-victim incidents during July 1994–June 2018.*

Incidents involved the homicide of at least one youth aged 5–18 years, but could also include nonstudent (e.g., school staff members or family members) homicides. However, this study provides characteristics and trends for youth homicide victims only and does not include adult homicide victim data. Incidents identified through the media scan were confirmed with accounts from local law enforcement or school officials familiar with the incident, and law enforcement reports were collected when possible. Incident characteristics (e.g., victim and perpetrator demographics, school affiliation, victim-perpetrator relationship, incident location, cause and manner of death, and firearm information) during July 1994–June 2016 were coded from law enforcement reports or interviews with law enforcement or school officials familiar with each incident. When interviews or law enforcement reports were not obtained, data were abstracted from articles published in the media only when a reliable source (i.e., a law enforcement or school official, or judicial proceedings regarding the incident) was cited. Finally, eight multiple-victim incidents from July 2016 to June 2018 were identified through Internet and online database searches; data for these incidents were abstracted from media articles citing a reliable source.§ Overall, media reports were solely relied upon for coding demographic and circumstantial details for 80 (18.6%) of 431 incidents.

Victimization rates were calculated for school-aged youths involved in single- and multiple-victim incidents. Incidence rates (using the number of incidents as the numerator) were also calculated for multiple-victim incidents. Both rates used U.S. Department of Education and Current Population Survey data on students enrolled in U.S. public and private primary and secondary schools by year as the denominator. National Center for Health Statistics mortality data for July 1994–June 2016 (the most recent school year for which data from both the School-Associated Violent Death Surveillance System and National Center for Health Statistics are available) served as the denominator for estimating the proportion of all homicides among school-age youths that were school-associated.[3] School-associated homicide trends were analyzed using Joinpoint regression based on Poisson distribution. For multiple-victim homicide victimization rates, to account for dependence between cases, the variance was estimated by applying a compound Poisson process based on data aggregated across 3-year intervals.[4]

During July 1994–June 2016, 423 school-associated homicide incidents occurred, including 393 (92.9%) single-victim and 30 (7.1%) multiple-victim incidents (accounting for 90 youth homicides), representing 1.2% of all homicides among youths aged 5–18 years (39,208) in the United States during this period. Further, three multiple-victim incidents occurred during July 2016–June 2017, and five occurred during July 2017–June 2018, accounting for 31 additional youth homicides.

Single-victim homicide decedents were mostly males (77.4%) and aged 15–18 years (77.9%), whereas multiple-victim decedents were evenly distributed among females (50.4%) and males (49.6%), and nearly a quarter were aged 5–9 years (Table 1). The single-victim homicide rate was highest in urban (0.07 per 100,000), public (0.037), and high schools (0.091), and was 8.27 times higher for non-Hispanic black youths than for non-Hispanic white youths (Table 2). Among those with known motives, gang-related activity (58.2%) and interpersonal disputes (44%) were the most common motives for single-victim homicides. Retaliation (e.g., due to bullying, rivalry between peer groups, or receiving bad grades from a teacher) (39.0%) was the most common motive for multiple-victim homicides, followed by gang-related activity (34.1%) and interpersonal disputes (29.3%). When single-victim incident perpetrators were known, the most common relationships between perpetrator and victim were stranger (27.6%), rival gang member (23.8%), or schoolmate/fellow student (21.2%). Multiple-victim homicide perpetrators were primarily strangers (36.2%) or schoolmates (36.2%) of their victims. Ninety-four (23.9%) single- and five (13.2%) multiple-victim incidents involved more than one perpetrator.

Firearm injuries were the cause of death in 247 (62.8%) single-victim school-associated homicides and 35 (92.1%) multiple-victim incidents that resulted in 115 (95%) youth homicides (Supplementary Table, https://stacks.cdc.gov/view/cdc/61748). Among these, more than one firearm was used in 10 (4.0%) single-victim and five (14.3%) multiple-victim incidents. In addition, 40.0% of single-victim and 60.5% of multiple-victim homicide perpetrators who used firearms were aged <18 years.

Overall, the average rate of single-victim school-associated youth homicides during July 1994–June 2016 was 0.03 per 100,000 students, and the average rate of multiple-victim school-associated homicides during July 1994–June 2017 was 0.008 per 100,000 (Table 2). Single-victim homicide rates increased significantly from July 2000 to June 2007 after a decline since July 1994; however, the rate did not change significantly over the entire period (p = 0.3) (Figure 1). Multiple-victim homicide victimization rates fluctuated substantially annually, but did not indicate a significant trend for the overall period (p = 0.6) (Figure 2). However, multiple-victim homicide incidence rates declined during July 1994–June 2009 and then increased through June 2018. Incidence rates fluctuated substantially (range = 0–6 incidents per year), and the recent increase likely was related to eight incidents that occurred during July 2016–June 2018.

Figure 1.

Victimization rates* for school-associated single-victim homicides per 100,000 students — United States, July 1994–June 2016
* Victimization rates were calculated as number of school-aged youth victims (i.e., aged 5–18 years) as the numerator and number of students enrolled in U.S. primary and secondary public and private schools as denominators. For single-victim school-associated homicides, incidence rates are equivalent to victimization rates. Single-victim homicide trends were analyzed using Joinpoint regression based on Poisson distribution, and the predicted rates from the model are shown as modeled rates.

Figure 2.

Victimization* and incidence rates of school-associated multiple-victim homicide per 100,000 students — United States, July 1994–June 2018§
* Victimization rates were calculated as number of school-aged youth victims (i.e., aged 5–18 years) as the numerator and number of students enrolled in U.S. primary and secondary public and private schools as the denominator.
Incidence rates were calculated as number of school-associated youth homicide incidents as the numerator and number of students enrolled in U.S. primary and secondary public and private schools as the denominator.
§ School-associated homicide trends were analyzed using Joinpoint regression based on Poisson distribution. For victimization rates, to account for dependence between multiple-victim cases, the variance was estimated by applying a compound Poisson process based on data aggregated across 3-year intervals. The predicted rates from the model are shown as modeled rates.

* Approximately 36,000 news articles per school year are reviewed in the media scan to identify an average of 50 potential single-victim cases annually. The validation of cases and access to incident data creates data lags. Manual Internet searches using phrases such as "school shooting" and "multiple victims and school" and web-based firearm injury data sets (i.e., Everytown for Gun Safety and the Gun Violence Archive) enhance the validation process and facilitate access to incident data for multiple-victim incidents. The overall process resulted in data currently being available for single-victim incidents through June 2016 and multiple victim incidents through July 2018.
Although all incidents in this study involved school-aged youths, some youths might not have been enrolled as students in a school.
§ 2016–17 and 2017–18 multiple-victim cases were identified through manual Internet searches using phrases such as "school shooting" and "multiple victims and school," as well as supplementary review of web-based firearm injury data sets (i.e., Everytown for Gun Safety and the Gun Violence Archive) to identify cases matching the School-Associated Violent Death Surveillance System case definition for multiple-victim youth homicides. Demographic and circumstance data for these cases were abstracted from media sources that referenced reliable sources as described above.
National Center for Education Statistics Common Core of Data, Public School Universe Survey, Private School Universe Survey, and State Nonfiscal Public Elementary/Secondary Education Survey were used to identify the number of students enrolled in U.S. public and private schools by race/ethnicity and school locale for rate calculation denominators. These calculations were limited to grades K–12. National Center for Education Statistics data were available only through the 2016–17 school year. Data from the 2017–18 school year are not yet available; thus, rate calculations for multiple-victim homicides (n = 93) are for the period from 1994–95 through 2016–17. U.S. Current Population Survey data on all students enrolled in U.S. schools by sex, school type, school level, and school year were used for denominators. Calculations using Current Population Survey data were limited to students aged 5–18 years and enrolled in grades K–12.

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