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Gang Homicide: The Road so Far and a Map for the Future
Jose Antonio Sanchez1
Scott H. Decker2
David C. Pyrooz1
1University of Colorado Boulder, Boulder, USA
2Arizone State University, Tempe, USA
Corresponding Author:
Jose Antonio Sanchez, University of Colorado Boulder, 483 UCB, Boulder, CO 80309-0401,
USA. Email: jose.sanchez@colorado.edu
Author’s Note:
Article published in Homicide Studies
This is a pre-print. Please download and cite the article from the Homicide Studies website:
https://journals-sagepub-com.colorado.idm.oclc.org/doi/full/10.1177/10887679211043804
DOI: 10.1177/10887679211043804
Abstract
Gang research has spanned nearly a century. In that time, we have learned that gang membership
increases the chances of involvement in homicide as a victim or offender. The violence that
embroils gang life, both instrumental and symbolic, often has consequences. In this paper we
review the gang homicide literature covering topics such as definitional issues, available data,
correlates and characteristics, and theoretical explanations. The review examines individual,
group, and structural contexts for gang homicide. We conclude with a discussion of future needs
in theory, data, and methods, to improve our understanding of gang homicide.
Keywords
gangs, homicide, violence, future directions, policy
Sanchez, Decker, and Pyrooz 1
Introduction
We were pleased to be asked to contribute to this volume, recognizing 25 years of the
journal, Homicide Studies. Our task is to review the literature on gang homicide, an important
part of all homicide. While this task may appear simple enough, it is not without its challenges.
There have been several reviews of gang homicide research. One such review was written by
Pizarro (2017), the editor of Homicide Studies (see also Corsaro et al., 2017; Lauger & Densley,
2018; Valasik & Reid, 2019). Our challenge lays not in rehashing what has been done but instead
finding something new to say about the topic. This is not to say gang homicide research has
remained stagnant.
Figure 1. Trend in interest in Gang Homicide, Google Books Ngram Viewer, 1950–2019.
Work on the spatiotemporal patterns and contagious nature of gang homicide would immediately
render such a conclusion false (e.g., Brantingham et al., 2020; Lewis & Papachristos, 2020).
Gang violence and homicide has been a part of gang research since its beginnings in the
late 1920s. Early attention to the topic comes from Asbury (1927) who spoke about gang
Gang Homicide 2
murders moving from one location to another, from continents to neighborhoods. Similarly,
Thrasher (1927; citing Yarros, 1926) identified Chicago as “the murder capital of the world”
largely as a consequence of gang homicides. Gangs adopting names such as “Murderers”
undoubtedly spurred embellished imagery of gang violence. Thrasher identified gang names as a
method of “wish fulfillment,” or the projection of an image to the gang, rival gangs, and
neighbors.
We begin with a figure (Figure 1) depicting the number of times that the term “gang
homicide” was used in books, based on a Google NGram search. A Google NGram charts the
frequency a particular word is used in a corpus of books, in this case the presence of the phrase
“gang homicide.” The 1980s and 1990s were decades of growth in attention to gang homicide.
Interest in homicide remained elevated in the new millennium, coinciding with trends in research
output on gangs (Pyrooz & Mitchell, 2015). The first volume of the journal Homicide Studies,
published in 1997, occurred near the initial peak of this interest. Still, in its history, based on our
searches, the journal has only published six articles on gang homicide (Cohen et al., 1998;
Costanza & Helms, 2012; Decker & Pyrooz, 2010; Jensen & Thibodeaux, 2013; Valasik et al.,
2017; Valdez et al., 2009). This represents around 1% of the total number of articles published in
Homicide Studies, which we believe far underrepresents the magnitude of the problem.
Gang homicide research faces several challenges. One such challenge is the defining of
gangs and gang crimes. What is a gang? What is a gang crime? A second key challenge is the
determination of what the unit of analysis is. Are we studying the gang? The gang member? Or
the crime committed by the gang member(s)? Short (1985, 1998) spoke at great length about
levels of measurement and the implications these have to gang research. This notion was echoed
Sanchez, Decker, and Pyrooz 3
by Decker and Pyrooz (2021) in their contribution to the Festschrift honoring Jim’s career.1 We
believe that there need not be an “either/or” and that each of the three are appropriate candidates
for explanation, provided there is appropriate data to measure each of them. Such perspectives
not only are necessary for a more accurate picture of gang members, but may have implications
for programming, intervention, and prevention. A third challenge is data. What data sources are
available to shed light on gang homicide? Nested within this challenge are definitional and unit
of analysis issues, particularly around biases that may emerge in classifying a “gang” homicide.
In this article, we aim to accomplish two things. First, we will provide a brief overview of
the gang homicide literature focusing on: (1) how gangs and gang crime are defined and the data
available for the study of gang homicides, (2) what separates gang homicides from other forms
of homicide, and (3) theory and research on gang homicide across levels of explanation:
community (macro), group (meso), and person (micro). Second, we discuss recent work being
done on gang violence and conclude with future directions worthy of continued exploration for
homicide researchers. The aim is to chart what should be accomplished in the next 25 years of
research on gang homicide.
Definitions and Data
The key to understanding the involvement of gangs and gang members in homicide
begins with an appreciation of the difficulty in defining the problem. Like many topics in the
study of violence, the definitional issues are complicated as are the subjects of many debates
over measurement and method. Gang research has always struggled with arriving at a consensus
operational definition of gangs, gang members, and gang crimes (Katz & Jackson-Jacobs,
1 An important component of his early work includes the book Homicide and Suicide, written with Andrew Henry in
1964.
Gang Homicide 4
2004).2 Variation in defining gangs is not limited to just academics. Indeed, great variation can
be found in legislation from the federal to the state level.3
There is only one group of stakeholders responsible for the systematic classification of
gang homicide: law enforcement. While researchers have undertaken efforts to review homicide
case files to examine gang homicide (e.g., Hipp et al., 2010; Pizarro & McGloin, 2006;
Rosenfeld et al., 1999) these are one-off occurrences, as classification is taxing and data access
can be fleeting. Law enforcement will typically classify gang crime as either: member-based or
motive-based.4 The first approach defines a gang crime based on the participation of a gang
member in a criminal act, either as a victim or an offender. For example, on May 20th, 2021, a
reported Blood gang member in Las Vegas felt disrespected by another man. As a response, the
suspect shot the victim who later died from his wounds (Puit, 2021). Motive-based requires the
incident to be perpetrated for the gang’s benefit. On June 13th, 2016, a member of MS-13—
having received permission from gang leaders—lured a teenager to a park in a Houston suburb
where he was killed by several MS-13 members in retaliation for the teen having aided law
enforcement (Sternitzky-Di Napoli, 2021). This incident would meet the motive-based criteria as
it was carried out for the benefit of the gang. The motive-based approach is obviously more
restrictive than just member-based.
There are other consequences to the choice of definition of gang crime, particularly for
gang homicide. Maxson and Klein (1990, 1996) compared homicides in Los Angeles using both
the gang member definition and the gang motive definition. The member-based definition yields
2 For a discussion and overview on the debates of gang definitions see (Curry, 2015). In many ways, Curry’s career
was devoted to improving the measurement of gangs, gang crimes, and gang membership.
3 This is partly due to variation in state and local legislation. For example, California was the first state to introduce
legislation in 1988 and defines what constitutes a gang but not a gang member. Nebraska, one of the last states to
introduce gang legislation in 2009, defines both gangs and gang members. Several states, such as Vermont, do not
have any legislation addressing gangs.
4 Member-based or motive-based are often also described as gang-related or gang-motivated, respectively.
Sanchez, Decker, and Pyrooz 5
nearly twice as many gang-related homicides as the narrower gang-motive definition. Another
crucial finding was that regardless of the definition used, the demographic characteristics of the
individuals involved (race, age, and gender) and the situational characteristics (guns, location,
victim offender relationship) of the events for motive and member-based definitions were the
same.
There are four national-level sources of data used to understand the nature and extent of
gang homicide since the founding of Homicide Studies.5 These include the Supplemental
Homicide Report (SHR), National Violent Death Reporting System (NVDRS), and the National
Death Index (NDI). The National Youth Gang Survey (NYGS) operated from 1996 to 2012.
These are the most representative data sources available, though it is important to highlight that
there are many studies that cover states, cities, and neighborhoods. As we will discuss in further
detail each of these data sources have strengths and limitations in the way they measure and
operationalize gangs and gang homicide.
We begin our discussion with the SHR. The SHR is collected as a part of the FBI’s
Uniform Crime Report (UCR) (Kaplan, 2021). UCR data has been collected for nearly 90 years
making it the longest running source of crime data in the US. Law enforcement agencies submit
SHR data on a monthly basis directly to the FBI or to a UCR coordinating agency. The current
iteration of the SHR can be traced back to 1976 when it was updated to include data such as gang
homicides. The unit of analysis for the SHR is incidents and may not be compared to the UCR’s
data which is focused on crime. The SHR provides data on two gang homicide types: (1)
gangland killings and (2) juvenile gang killings. From 2000 to 2019, the most current year data
are available for the FBI, through the SHR, has reported 3,423 gangland killings and 12,806
5 More accurately, there are three sources that are still collecting data: SHR, NVDRS, and NDI. The NYGS was
dropped in 2012 due to “funding reasons” according to NGC director Meena Harris (Asher, 2017). In 2020, the
National Institute of Justice awarded the RAND Corporation a grant to restart the NYGS (2020-JX-FX-K007).
Gang Homicide 6
juvenile gang killings—around 800 murders per year (FBI:UCR, n.d.). Issues of inconsistent
operationalization and lack of local law enforcement oversight on these two types has prevented
the SHR from being widely used in gang homicide research.
To date, three studies have examined the NYGS, two of which examined the NYGS and
SHR concurrently. Decker and Pyrooz (2010) compared the SHR and the NYGS among the 100
largest cities in the United States. The NYGS exhibited satisfactory reliability properties over
time with internal benchmarks both in cities with and without dedicated gang units. However,
measurement properties of the SHR were much weaker and the data are limited to youth gang
homicides. Focusing on youth gang homicides results in underreporting of homicides since these
crimes tend to be carried out and experienced by young adult gang members (Maxson, 1999). A
second study on the validity of the NYGS expressed caution as the reliability of the data was not
strong for cities with populations under 200,000 persons (Katz et al., 2012). This leaves us with
two criminal justice measures (both based on police reports) with less than satisfactory
measurement properties, particularly the SHR. Finally, Jensen and Thibodeaux (2013) studied
whether media coverage of gang homicides were creating a false panic or if they tracked on to
data sources collecting information on gang homicides (the SHR and NYGS). They found that
media cover- age of gang homicides tracked well with the NYGS and even better with the SHR.
The National Violent Death Reporting System (NVDRS) consists of data from multiple
sources, generally a strength in measurement. The NVDRS includes information from law
enforcement, medical examiners and coroners, toxicological information, and death certificates.
The NVDRS database has been underutilized by criminologists in the study of gang homicide, a
persistent shortcoming of criminologists who rarely venture far afield from criminal justice data.
Egley et al. (2012) compared the NVDRS to the NYGS and found the cities in their NVDRS
Sanchez, Decker, and Pyrooz 7
study also demonstrated high gang-related mortality rates in the NYGS. The NVDRS has, until
recently, been limited in its geo- graphic coverage of areas that classify gang homicides (e.g., big
cities). For example, in 2002, only six states were included in data collection. However, since
2018 the NVDRS has collected data from all 50 states, Puerto Rico, and D.C. (CDC, n.d.).
In their analyses of these data, Frazier et al. (2017) introduced a category of “gang- like”
homicides. In so doing, they argued that gang homicides may be underrepresented in current data
even when gang-member (or gang-related) definitions are used. Their approach included four
criteria for identifying a gang homicide: (1) a weapon being used, (2) location being on the
street, driveway, or porch, (3) circumstances of the incident (e.g., drive-by, or gangland killings,
among others.), and (4) a prior relationship with the victim (excluding friends or romantic
partners). To qualify as “gang- like” three of the four criteria had to be present. This resulted in a
“substantial increase” in the total number of gang homicides recorded. This approach is not
without controversy, both on conceptual and methodological grounds. It is not fully justified why
only three of four criteria had to be present as opposed to all four, and a test of this presumption
would benefit the discussion. Furthermore, only 37% of the gang-related homicides in the
NVDRS data met their gang-like criteria. It is not properly explained why not all gang-related
incidents were captured by the gang-like criteria which should be the case if their criteria is to
capture a more accurate representation of homicide figures. The controversy over definitions and
measurements continues with attempts to impose the gang label on homicides by Frazier and
colleagues.
Another public health data source seldom used by criminologists is the National Death
Index (NDI). The NDI is a component of the National Vital Statistics Systems, an annual
compilation of death information drawn from state provided death certificates. Tostlebe et al.
Gang Homicide 8
(2021) examined the reliability of the NDI by linking it with data sources that identify deceased
persons and their cause of death. When they linked the NDI to a St. Louis Metropolitan Police
Department gang database, the authors found that of the 285 of the 3,120 gang members in their
sample had died, and the cause of death for just under half was assault. Of the 141 people whose
death was the result of an assault, 135 deaths involved a firearm, a staple of gang violence. This
translated into an age-standardized homicide rate of 950 per 100,000, which was three times
higher than comparable age black males in St. Louis and nine times higher than com- parable age
black males in the United States (Pyrooz et al., 2020). These comparisons of data sets are most
useful for establishing reliability as well as assessing the overlap of public health data with
criminal justice data.
Correlates of Gang Homicide
There are four correlates that distinguish gang from non-gang homicide: firearms, drugs,
public settings, and the demographics of suspect-victim relationships. We high- light these
correlates in that order.
The disproportionate role of firearms in gang-related homicides is perhaps the most
notable of the correlates of this type of homicide, a consistent finding over the past 25 years of
gang research. Indeed, guns and gangs have become synonymous with one another. It is not
uncommon to see gang members posting pictures of themselves holding firearms on social media
(e.g., Patton et al., 2017). An increase in firearm accessibility raised the lethality of gang conflict
and altered the landscape of gang violence (Miller, 1975). Decker et al. (1997) found that self-
reported gang members were more likely than any other group of arrestees to report wanting,
owning, using, or being victimized by firearms. Bjerregaard and Lizotte (1995) and Lizotte et al.
(1994) reported that gun ownership remained one of the strongest correlates of gang member-
Sanchez, Decker, and Pyrooz 9
ship and gang violence. Lizotte et al. (1994) reported that youth who carry guns for protection
are five times more likely to be in a gang than youth who own guns for sporting purposes.
Firearms are the weapon of choice among gang members, a preference for ownership that has
increased over the course of the past four decades (Howell, 1998). This fact appears to be linked
closely to the increased lethality of gang assaults (Block & Block, 1993).
Around 71% of gang homicides involved a firearm in the late 1970s. That rose to well
over 90% of gang homicides in the 1990s (Block & Block, 1993; Hutson et al., 1995). In
addition, firearms are intimately linked to a particular and highly publicized form of gang
violence: drive-by shootings (Sanders, 1994). In Los Angeles one estimate is that during a 5-year
period one-third of gang homicides occurred during a drive-by shooting (Hutson et al., 1996).
Sanders (1994) characterized gang life by stating “the violent aspects of gang life are always
there – either defensively or as an offensive option” (p. 146), a view echoed for St. Louis gang
members whose lives are characterized by “threat” from rival gangs, one’s own gang, and the
police (Decker & Van Winkle, 1996). What makes the drive-by shooting the quintessential gang
crime is that it is unpredictable, generates considerable fear among gang and nongang members
in communities, and creates intimidation among gang and community residents alike (Howell,
1998). Gangs not only recruit youth who have access to firearms, they can significantly facilitate
access to firearms as well (Bjerregaard & Lizotte, 1995; Roberto et al., 2018). Contrary to
popular belief, the firearms used by gang members are not stolen by the gang members. Instead,
gang members are more likely to purchase guns from traffickers who made legal and illegal
purchases (Hureau & Braga, 2018). Gang members will leverage established connections to
expedite their acquisition of guns (Braga et al., 2020). Roberto et al. (2018) noted that
heightened access to guns also resulted in increased risk for gun victimization generally. There
Gang Homicide 10
had been a lull in research on links between gangs, gang members, and gun crime. The recent
work involving Braga and colleagues is a welcome addition to this discussion, though more is
needed.
The overlap among drug use, drug trafficking, and involvement in violent crime that
involves gang members. Howell and Decker (1999) concluded that there was substantial overlap
between involvement in drug markets and the use of violence. Block and Block (1993) identify
disputes over drug turf as being at the heart of a considerable amount of gang violence.
Similarly, Klein et al. (1991) documented the substantial involvement of gang members in drug
sales. A host of ethnographic studies (Decker & Van Winkle, 1996; Hagedorn, 1994, 1998;
Vigil, 1988) have documented that gang members are extensively involved in the sale of drugs.
Drug use among gang members has also been reported in a host of studies (Decker & Van
Winkle, 1996; Hagedorn, 1989; Howell & Decker, 1999). Bellair and McNulty (2009) conducted
one of the few studies that contradicts the null findings widely found in gang research examining
gang members, drugs sales, and violence. They found that gang members who sold drugs,
especially those in disadvantaged neighborhoods, were more violent than non-drug selling gang
members. Despite this involvement, a causal relationship between gangs and drugs sales is
generally not supported by the empirical literature. As with the role of guns in gang life, more
contemporary attention to the role of drugs in violence escalation or spread is needed.
Gang homicide is usually carried out by gang members who are young adults. Studies in Los
Angeles, St. Louis, and Newark found the age of gang homicide suspects were between 19 and
24 (Decker & Curry, 2002; Maxson et al., 1985; Pizarro & McGloin, 2006). Victims are also
younger than in other homicide types. For example, Maxson (1999) reported victims in Los
Angeles were about 24. We should note that suspects and victims of gang homicide are younger
Sanchez, Decker, and Pyrooz 11
than suspects and victims of other forms of homicide but older than the average gang members
(Maxson, 1999; Pyrooz, 2014). It is typical for the suspect and victim to have had a prior
relationship, insofar that intra-gang killings are not uncommon (Decker & Curry, 2002; Pizarro
& McGloin, 2006; Valasik & Reid, 2021).
Gang homicide typically occurs in public places. Maxson et al. (1985) reported that over
70% of gang homicides in their sample occurred in public. A study of East Los Angeles found
that 68% of the gang homicides analyzed happened on the streets (Valasik & Reid, 2021). Gang
homicide victims are likely to be away from home and suspects are more likely to travel further
distances than suspects for other types of homicides (Pizarro et al., 2007). Finally, gang
homicides are likely to be concentrated in areas of socioeconomic disadvantage (e.g., Mares,
2010; Valasik et al., 2017; Zeoli et al., 2014).
Theories of Gang Violence and Homicide
Gangs have long been a crucible for the development of criminological theory; indeed
strain, subcultural, conflict, and group process theories of delinquency and crime all have their
roots in gang research, programming, or theory (Decker et al., 2021). Theories of gang violence
and homicide have focused on three levels of explanation: structural or community levels
explanations, group process, and (rarely) individual level explanations (Pizarro, 2017), which
reflect the organizational schema identified by Decker et al. (2013). Below we will provide an
overview of these theories.
The Macro: Structural and Community-Level Theories
Structural and community level explanations focus on the composition and contextual features of
aggregated geographical space (states, counties, cities, or neighbor- hoods). From this
perspective, concentrations of negative structural indicators such as concentrated disadvantage,
Gang Homicide 12
abandoned buildings and low civic engagement lead to higher levels of violence including gang
homicide. Papachristos et al. (2013) described “the corner,” which indicates the spatial locations
inhabited by gangs and where violence is usually found. There is a bidirectional relationship
between gangs being a product of their environment and contributing to such an environment.
Structural and community-level explanations typically include measures of ethnic and racial
composition, poverty, gun availability, and the presence of drugs (whether selling or using)
(Rosenfeld et al., 1999). These approaches often make use of spatial analyses which are built
upon comparative analyses—across neighborhoods, cities, and/or states (Barton et al., 2020;
Cohen & Tita, 1999; Valasik, 2018).
In an early application of social disorganization theory to gang violence, Curry and
Spergel (1988) examined homicide and gang delinquency among both Latinos and African-
Americans in Chicago. They concluded that gang homicides have a significantly different
ecological pattern than do non-gang homicides and conform to classic models of social
disorganization and poverty. They argue that conceptualizing gang groups as a function of
mobility patterns is a productive conceptual means of under- standing gang homicides. Thus, in
neighborhoods in the process of undergoing shifts in population composition, overall mobility,
and economic change, social disorganization was likely to be found. This disorganization was
subsequently linked to gang homicide and other forms of gang crime, particularly violence.
The spatial concentration of gang violence has been documented in a number of cities
(Boston, Chicago, Los Angeles, and St. Louis). In Boston, Kennedy et al. (1998) reported an
especially strong spatial concentration among gang homicides and document that with a very
useful sociogram depicting the conflict between gangs. These findings were in line with those
reported by Block (1991) for Chicago and by Maxson (1999) for Los Angeles. Similarly, Tita et
Sanchez, Decker, and Pyrooz 13
al. (2003) have documented the strong spatial concentration of gang violence in the South
Central neighborhoods of Los Angeles and the role of inter-gang conflict. Such events
disproportionately involve gun assaults, firearms, and drugs. This finding is similar to that
reported by Rosenfeld et al. (1999) for St. Louis, as well as by Lewis and Papachristos (2020).
Papachristos and Kirk (2006) examined the impact of collective efficacy on gang
homicide at the neighborhood level. They found partial support for that perspective, but they also
noted that some neighborhoods experienced gang violence while other similar neighborhoods did
not. Mares (2010) found support for several tenets of social disorganization except for
instability.6 Similarly, most of the empirical research examining the geographic characteristics of
gang violence has been done within cities and not between cities, largely owing to the lack of
comparable measures. This has led to conflicting evidence regarding which correlates truly
matter, leaving us with a rather incomplete picture of this important relationship (for a review,
Decker et al., 2022).
There are not many macro-level or city analyses of gang homicide. Pyrooz (2012) is one
of the few to study differences across cities (see also Jackson, 1991), examining the structural
covariates of gang and non-gang homicides. He found that socioeconomic deprivation and
population density predicted both gang and non-gang homicides. Conversely, population density
was stronger as a predictor for gang homicide than non-gang homicide. The territorial nature of
gangs may serve to concentrate gang violence in specific areas of a city. The second key finding
was that higher levels of socioeconomic deprivation and population heterogeneity contributed to
higher rates of gang membership, which in turn was associated with higher rates of gang
homicide.
6 A possible explanation for this finding is that if gangs are experiencing high levels of instability it means they are
experiencing high levels of turnover which would threaten their longevity (see Katz & Schnebly, 2011).
Gang Homicide 14
Valasik et al. (2017) studied gang homicide in the Hollenbeck precinct of Los Angeles.
Their work is at the forefront of research examining structural processes and gang homicide.
Consistent with Pyrooz (2012), Valasik et al. (2017) determined that disadvantaged areas and
areas with higher levels of social disorganization were associated with higher risks for gang
homicides. Their work showed that gang violence clustered in specific neighborhoods regardless
of disadvantage or year of study. Gang violence was not randomly distributed; physical
structures influenced where gang violence took place. Valasik’s (2018) research Hollenbeck
underscored the importance of places where people interacted on a routine basis such as public
transit had a higher risk for increased levels of gang assaults and homicides (Valasik, 2018).
The Meso: Group Process
A subgroup of studies of gang homicide have focused on the social processes involved in
the generation of such violent events (Loftin, 1986). Such analyses focus on the dynamics of
interactions that lead to initial and retaliatory acts of gang violence. In gang homicide, the initial
act is seldom as complicated as the response to the initial act. This level of analysis is consistent
with the middle-level or meso explanation encouraged by Short (1985, 1989), who underscored
the role of group process and social-psychological variables in the understanding of gangs and
gang activities. Features of gangs and gang activity include examples of turf adjacency, prior
conflict, reciprocity (i.e., retaliation), and status seeking. In the context of understanding
violence, such variables are particularly important as much gang violence has institutional
memory, retaliatory character, and cognitive maps of people, turfs, and groups (i.e., the gang
landscape).
Unlike community-level explanations, mid-range, or meso approaches contend that
violence is an outcome of group processes that are endogenous to the gang. While Thrasher
Sanchez, Decker, and Pyrooz 15
(1927) discussed group processes, it was nearly 40 years later that Short and Strodtbeck (1965)
revisited this perspective in a systematic way. They argued that dynamics internal to gangs and
external dynamics between gangs could be used to explain violent behavior, including gang
homicide. This perspective hinged on the role played by threats to gang status mobilizing
violence. Short and Strodtbeck observed that status threat was pronounced among gang leaders
who resorted to violent out- bursts when their leadership or dominance within the gang was
threatened. The status- threat concept was expanded upon by Decker (1996), who found that
gang violence was exacerbated by the weak leadership often found in gangs. Another key to
Decker’s analysis was that threats were identified collectively in the gangs and served to unify
members to mobilize and repel threats (real or exaggerated) from rivals.
Recent work by Lewis and Papachristos (2020) underscored the interactions of
individuals engaged in “homicide networks” paying particular attention to the “rules of the
game” as they are understood on the street. Using Short’s Chicago Data, Hughes (2013)
examined the relationship between the behavior of gang members and prestige within the gang.
This led to more crime and violence as status threats were widespread and there were few
mechanisms in place to resolve conflicts over threat. Hughes et al. (2021) observed that areas
with higher concentrations of gang graffiti— a symbolic way of marking territory or
disrespecting a rival gang—were strongly associated with gang homicides, net of neighborhood
characteristics. These findings lend further support to the threat hypothesis because graffiti “is a
subcultural means of communication that facilitates group processes associated with violence,
such as identification of an out-group as a common enemy and existing threat.” (Hughes et al.,
2021, p. 6).
Gang Homicide 16
Pizarro and McGloin (2006) provided support for a collective behavior approach to
understanding gang homicide. Using 5 years of homicide data from Newark, they compared the
explanatory power of social disorganization and escalation variables in explaining patterns of
gang homicides. Gang homicides were characterized by the use of firearms, crimes committed
outside, the involvement of multiple suspects, and an acquaintance relationship between victims
and offenders. The key escalating factor was threat, either against the group (gang) or the status
of the group. Their findings clearly supported explanations based on social process compared
over structural variables in explaining the difference between gang and nongang homicides.
Structural variables are also important to understanding the process involved in gang homicide.
Corsaro et al. (2017) identified that different “types” of gang homicides involve different
patterns and means of arriving at the “scene” of the violence. This underscores the importance of
understand the events, motivations and actors leading up to and following a homicide event.
The Micro: Individual Level Theories
Individual level explanations constitute, arguably, the most deficient body of gang
homicide literature. Yablonsky (1962) is the most notable exception in this regard, and the fact
that his work is nearly 60 years old speaks to the paucity of research in this tradition. Yablonsky
described youth who joined gangs as sociopaths—impulsive, callous, and untrustworthy. The
sociopathic adolescents described by Yablonsky bear a strong resemblance to Gottfredson and
Hirschi’s (1990) theory of self-control and the Thornberry et al. (1993) selection hypothesis.
Individual level explanations argue it is not the community or group socialization processes that
lead young people to join gangs or engage in gang violence. Rather, it is the common orientation
toward violence they share with other individuals that leads them to form groups and engage in
violence. This “birds of a feather” approach has failed to generate much support in the research
Sanchez, Decker, and Pyrooz 17
or practice literature. Both Klein (1971) and Pyrooz et al. (2021) find little support for the
individual difference approach. However, this is not a call to eliminate individual level theories.
Indeed, support has been found with individual traits—such as behavioral disabilities—factoring
into violent behavior by gang members (DeLisi et al., 2019).
There are other individual-level theories that apply to gang violence, although they also
place theoretical weight on the environment in which people are situated. Cohen and Felson’s
(1979) routine activity theory and Hindelang et al. (1978) lifestyle theory have been applied to
the study of gang membership and victimization (Peterson et al., 2004; Taylor et al., 2007; Wu &
Pyrooz, 2016). Emerging work in the UK (Coid et al., 2020; Wood et al., 2020) provides some
support for the individual level approach.
Future Directions in Gang Homicide Research
We conclude this review by highlighting key areas that future research on gang homicide
should address. Specifically, we will discuss three broad areas: theory, data, and methods.
Improving these areas will be critical for research in this area as policy and practice can be
greatly impacted by research in this area. Had we written this article a generation ago (and one of
us did) the call would have been the same. Indeed, improved theory, data and methods is a
common trope in conclusions, particularly articles that serve to review the state of literature.
While much has improved, there is still work to be done, and there should be optimism that
much of the needs can now be addressed. We would also like to note that many of the
recommendations we will discuss are not mutually exclusive but rather intertwined. Addressing
these gaps would push the effectiveness of programming forward.
Gang Homicide 18
Gang Homicide Theory
As we discussed in our review of theoretical explanations, despite almost a century of gang
research, the cupboard of theoretical explanations of gang homicide is mostly bare. Macro level
theories dominate this area building upon the social ecology perspectives of the Chicago school
(Burgess & Park, 1925; Shaw & McKay, 1942; Thrasher, 1927). With few exceptions (e.g.,
Papachristos & Kirk, 2006), the bulk of empirical research concentrates on structural factors
rather than mediating mechanisms (Decker & Pyrooz, 2021). Studies testing the tenets of
individual level theories such as self-control (e.g., Pyrooz et al., 2021) and the selection
hypothesis (e.g., Fox et al., 2013; Matsuda et al., 2013; Wu & Pyrooz, 2016) have been
conducted but they are scarce and have provided mixed results.
Group process explanations are in a similar state. Status threat has been explored by
Short and Strodtbeck (1965), Hughes (2013), and Decker (1996). Klein (1969) posited gang
cohesion was key to explaining gang violence. Hughes (2013) found contradicting evidence.
However, there have been calls to keep cohesion as a vital aspect of gang research and further
explore variance and importance of cohesion to the gang (Hennigan & Sloane, 2013;
Papachristos, 2013). Social network analysis has opened up rich lines of inquiry that were not
possible with traditional, variable-based inquiry (e.g., Papachristos, 2009), and we suspect will
continue to pay dividends to advancing our understanding of group process in the years to come.
We cannot stress enough that as our understanding of the causes of gang violence become
clearer, the more effective our strategies to address the issue become. We cannot hope to hit the
bullseye until the blindfold comes off.
Sanchez, Decker, and Pyrooz 19
Data Collection and Measurement
The call for better theory is also a call for better definitions of terms. Since gangs were
first a focus of study, analysts, reformers, researchers, policymakers, and practitioners have
struggled to use a common nomenclature in talking about gangs, gang members, and gang
crimes. Achieving such a goal in practice is difficult. Indeed, as the Eurogang Working Group
(Klein et al., 2000) has found, iron-fisted approaches to imposing common definitions are rarely
successful. The emergence of the Eurogang definition has allowed for comparative work not just
nationally but outside of US borders as well. However, the Eurogang definitions has just as many
detractors as believers. Even among those who have adopted the definition there are those who
remain skeptical. Matsuda et al. (2012) explored the overlap of gang member definitions—self-
nominAtion, Eurogang, friends are a gang—and found all three definitions only had a 9%
overlap. To this end, they state “This suggests that we may still have some way to go in
formulating a consensus definition that links up conceptual and operational definitions of youth
gangs.” (Matsuda et al., 2012, p. 48). The resurrection of the national gang survey formerly
conducted by the National Gang Center and now under the direction of RAND Corporation
offers significant hope that a scientifically defensible sample, based on consensus definitions is
again possible.7 Still, definitions are critical for understanding the problem (Esbensen et al.,
2001). As police departments move away from gathering intelligence on gangs, owing to
political or organizational influences, it is likely that even studies relying on law enforcement
reports of gang homicides will undercount homicides that are gang-related or gang-motivated
7 In 2008, a large Midwestern city received a $2 million grant to address gang crime. One requirement to accept the
funding was to document the gang problem in the jurisdiction. There was no operational definition of gang, gang
member or gang crime, and the police department had to use grant funds to code and document the gang problem.
(Cahill et al., 2008). Awareness on the ground is necessary not only for a better understanding of gangs but also for
programming and outcome evaluations.
Gang Homicide 20
(Densley & Pyrooz, 2020), which ups the stakes for identifying alternatives methods to study
gang homicide (e.g., Frazier et al., 2017).
The paucity of data describing gangs, gang members, and gang crime is remarkable.
There are few truly longitudinal studies with high quality gang data (e.g., Causes and Correlates
studies in Denver, Pittsburgh, and Rochester; National Longitudinal Survey of Youth 1997,
Pathways to Desistance, etc.), as the cost of such studies, the rollout and availability of the data,
and the learning curve for proficiency are substantial. Yet, we must consider what we have
learned from these data. In addition, law enforcement data on gangs, gang members and gang
crimes are plagued with inconsistencies in years collected, definitions, and availability.8 Recent
advances have been made in the collection of data from public health settings, particularly
emergency medicine settings and we have seen this approach implemented into gang
programming (e.g., Cure Violence; see Butts et al., 2015). The stakes are high for the RAND
Corporation in its development and administration of the national gang survey. A strength of the
National Gang Center was its integration of research and policy findings from governmental and
non- governmental agencies. One hopes to see such a focus sustained in the future. Clearly, the
need to integrate multiple data sources is imperative. We have seen successful linking of
multiple data sources to advance the study of gang homicide (e.g., Pyrooz et al., 2020; Tostlebe
et al., 2021). It would behoove us to follow suit and explore linking datasets, such as the Causes
and Correlates studies, with the NDI to obtain a clearer picture on gang member mortality risks.
Methods of analysis should remain a priority. Much has been learned from the analysis of groups
involved in crime through the methods of Ouellet et al. (2019), Papachristos (2009),
Brantingham et al. (2020), and others. Geographic analyses conducted by Braga, Tita and
8 Findings such as ethnic and racial minorities being more likely to be gang members and engage in gang homicide
could also be the result of biased law enforcement data (Esbensen & Carson, 2012; Esbensen & Winfree, 1998).
Sanchez, Decker, and Pyrooz 21
Valasik have pushed the field ahead in important ways. Papachristos’ work is particularly
important in this context because it integrates social network and geospatial analyses with strong
theory. Similarly, Valasik et al. (2017) merged temporal and spatial analytic tools to better
distinguish between gang and non-gang homicides. These are but some of the advances needed
to better understand gang violence and gang homicide. The work of Brantingham et al. (2020)
and Zeoli et al. (2014) have used network and spatial analyses to determine whether gang
violence can have a contagion effect. In other words, does gang violence spread in a way,
theoretically, similar to a virus? So far, it has been shown that it does.
Finally, program evaluations should become a higher priority for gang programs.
Blueprints—a database housing programs that have met rigorous evaluation criteria—currently
lists a grand total of zero gang intervention programs as having met its standards for either
promising or model program.9 As it stands, we cannot answer questions such as: do we need to
address an individual’s gang identity or should we focus solely on their behavior? In order to
properly address gang violence, we need to know what works. Programs like focused deterrence
have shown promise (see Braga et al., 2018) but as Roman et al. (2017) pointed out, these
programs may not yield the long-term effects desired and an emphasis to address individuals’
gang membership should be made.
Expanding the Boundaries of Research on Gang Homicide
The issues regarding group involvement in crime have become more complicated over the past
two decades. As we consider how best to define gangs, gang members and gang crimes, where
do other groups “fit” in such a description? Take Antifa and Alt-Right groups for example. Each
9 A “promising” classification is awarded to a program that has one experimental evaluation or two quasi-
experimental evaluations demonstrating significant effects on the stated out- comes. “Model” status is given to
programs that achieve replication in a separate site and intervention effects last 1 year after program completion.
Gang Homicide 22
includes groups of individuals who share common characteristics and beliefs, acknowledge
membership in a group, identify with the name and (loosely) with values espoused by the group.
When does a group, for which acts of law violation are an acknowledged component of
membership, become a gang? This question adds complexity to Thrasher’s classic depiction of
gangs sharing characteristics of delinquent and non-delinquent groups. It may be that multiple
definitions will be used, but their differences must be acknowledged and clearly articulated.
Some have done research on Alt-Right groups through the lens of street gangs (e.g., Reid &
Valasik, 2020).
The advent of the internet has opened a new social setting for criminologists to study. Those
studying gang violence and homicide are no different. Indeed, this is a burgeoning area of
research. The recent work of Lauger and Densley (2018) uses online sources to examine
depictions of homicide that play out on social media, a new and complex source of data for gang
research and theory (see also Moule et al., 2017; Patton et al., 2020; Stuart, 2020). This body of
research has revealed that threats and feuds on a virtual platform can spill over into real life
consequences, sometimes lethal. Gang members have also used social media to memorialize
their fallen brethren. One avenue that remains largely unexplored in this area is the use of the
internet, specifically social media, by practitioners to track gang members’ gang related activity.
As we highlighted earlier in this paper, gang homicide tends to take place in public
settings. But, gang members also get incarcerated and prison gangs are an issue (Pyrooz &
Decker, 2019; Skarbek, 2014). While recent data are difficult to find, national estimates of the
size of the incarcerated juvenile population that claims gang membership range from 40%
(Parent et al., 1994) to 78% (Knox & Tromanhauser, 1991). Among the adult population, that
estimate is lower, 15%, but still an order of magnitude greater than in the non-custodial, general
Sanchez, Decker, and Pyrooz 23
population (Pyrooz & Mitchell, 2019). Gang members in prison engage in disproportionately
high levels of violence (Ingraham & Wellford, 1987; Pyrooz & Decker, 2019). Data on gang
homicide within prison settings is scarce. Still, reports from the Bureau of Justice Statistics
indicates a very troubling trend in U.S. prisons: rising homicide rates (Carson, 2021). In the
aughts, there were 39 (2001), 40 (2008), and 54 (2009) homicides in state and federal
prisons. In the 2010s, those counts increased to 70 (2010 and 2011), 85 (2012), 90
(2013), and eventually to 113 (2017) and 120 (2018). No longer is the homicide rate lower inside
of prisons than outside of prison. What role have gangs played in these homicides, including the
rise in prison violence? This is undoubtedly an area of research that requires the attention of all
stakeholders.
Schools are another institution that can often deal with young gang members. Research in
schools is notoriously challenging to conduct. However, it could be worth- while to explore gang
homicides that result in educational settings or where the school setting plays a pivotal role in the
conflict. Again, most gang violence occurs in public on the streets. That does not mean it is the
only setting. After all, between 1970 and 2020, there were 221 instances of gang-related gun
incidents on school grounds, according to the Naval Postgraduate School’s Center for Homeland
Defense and Security. That constitutes 14% of the total gun incidents on school grounds.
Broadening our social settings could provide a much clearer picture as to the prevalence and
magnitude of gang violence.
Conclusion
Gang homicide research has come a long way in the last few decades. It is also true that
we have a long way to go still. However, the work being conducted gives us hope and
confidence that we are moving in the right direction. We have experienced setbacks (the
Gang Homicide 24
discontinuing of the NYGS) and much is still unknown (e.g., theoretically). It is our hope that
this article will inspire scholars to keep advancing our knowledge-base forward. The NYGS has
been given a second chance which could yield a great deal of knowledge, but we urge
researchers to draw on multiple sources of data and theories that span disciplines in order to
obtains an accurate representation of the problem and, hopefully, solutions for lessening gang
violence in the United States and beyond.
Sanchez, Decker, and Pyrooz 25
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Jose Antonio Sanchez is a doctoral student of Sociology and an affiliate in the Institute of
Behavioral Science at the University of Colorado Boulder. He received his B.S. and M.S. from
Cal State Los Angeles. His research interests include gangs and criminal netowrks, program
evaluation, responses to gang crime, and criminal justice policy and practice.
Scott H. Decker is a Foundation Professor Emeritus in the School of Criminology and Criminal
Justice at Arizona State University. His main research interests are in gangs, violence, and the
criminal justice system. He is a fellow in the American Society of Criminology and the Academy
of Criminal Justice Sciences. He is the author of nineteen books including Life in the Gang:
Family, Friends and Violence (Cambridge, 1996), Competing for Control: Gangs and the Social
Order of Prisons (Cambridge University Press, 2019, with David Pyrooz), and On Gangs
(Temple University Press, 2022, with David Pyrooz and James Densley). He was a member of
the Evaluation Team for the Proponte Mas program in Honduras.
David C. Pyrooz is an Associate Professor of Sociology at the University of Colorado Boulder.
He studies gangs and violence, incarceration and reentry, and criminal justice policy and prac-
tice. His recent book with Scott Decker, Competing for Control: Gangs of the Social Order of
Gang Homicide 42
Prisons (Cambridge University Press), was the 2021 recipient of the Outstanding Book Award
from the Academy of Criminal Justice Sciences.