Gun Offenders Research Articles

Predicting Short Time-to-Crime Guns: a Machine Learning Analysis of California Transaction Records (2010–2021)

Gun-related crime continues to be an urgent public health and safety problem in cities across the US. A key question is: how are firearms diverted from the legal retail market into the hands of gun offenders? With close to 8 million legal firearm transaction records in California (2010–2020) linked to over 380,000 records of recovered crime guns (2010–2021), we employ supervised machine learning to predict which firearms are used in crimes shortly after purchase. Specifically, using random forest (RF) with stratified under-sampling, we predict any crime gun recovery within a year (0.2% of transactions) and violent crime gun recovery within a year (0.03% of transactions). We also identify the purchaser, firearm, and dealer characteristics most predictive of this short time-to-crime gun recovery using SHapley Additive exPlanations and mean decrease in accuracy variable importance measures. Overall, our models show good discrimination, and we are able to identify firearms at extreme risk for diversion into criminal hands. The test set AUC is 0.85 for both models. For the model predicting any recovery, a default threshold of 0.50 results in a sensitivity of 0.63 and a specificity of 0.88. Among transactions identified as extremely risky, e.g., transactions with a score of 0.98 and above, 74% (35/47 in the test data) are recovered within a year. The most important predictive features include purchaser age and caliber size. This study suggests the potential utility of transaction records combined with machine learning to identify firearms at the highest risk for diversion and criminal use soon after purchase.

The Cost of Gun Crime: Evidence from Gun Offender Registry on Housing Values

In this study, we estimate the cost of gun crime using a revealed preference framework by relying on an institutional change in Baltimore City, Maryland, that mandates public disclosure of the gun offender registry. We exploit the sharp localized change in perceived crime risk after gun offenders move into the neighborhood and examine its impact on housing values in the vicinity. Our estimates indicate that houses closest to gun offenders experience 7.1% decline in value ($9,100) after the offenders move in, and the probability of sales is 43% lower. Collectively, public disclosure of a gun offender’s residence costs homeowners around $888 million. We construct a simple model to estimate the cost of gun victimization from these house price discounts. Based on our preferred specification, the cost of gun crime victimization is around $1.5 million and, assuming a 20% fatality rate, the value of statistical fife is approximately $9.0 million.

Why do gun murders have a higher clearance rate than gunshot assaults?

Research SummaryThe prevailing view is that follow‐up investigations are of limited value as crimes are primarily cleared by patrol officers making on‐scene arrests and through the presence of eyewitnesses and forensic evidence at the initial crime scene. We use a quasi‐experimental design to compare investigative resources invested in clearing gun homicide cases relative to nonfatal gun assaults in Boston. We find the large gap in clearances (43% for gun murders vs. 19% for nonfatal gun assaults) is primarily a result of sustained investigative effort in homicide cases made after the first 2 days.Policy ImplicationsPolice departments should invest additional resources in the investigation of nonfatal gun assaults. When additional investigative effort is expended, law enforcement improves its success in gaining the cooperation of key witnesses and increases the amount of forensic evidence collected and analyzed. In turn, the capacity of the police to hold violent gun offenders accountable, deliver justice to victims, and prevent future gun attacks is enhanced.

Gun Violence Following Inpatient Psychiatric Treatment: Offense Characteristics, Sources of Guns, and Number of Victims.

This study presents data on the relative contribution to gun violence by people with a history of inpatient psychiatric treatment and on federal efforts to deter presumptively dangerous persons from obtaining firearms, information useful for analyzing the potential public health benefits of gun policies targeting people with serious mental illness. The study also estimates the reduction in gun violence victims that would be expected if individuals with a previous psychiatric hospitalization were prohibited from purchasing firearms. Data from 838 violent gun offenders from a nationally representative sample of state prison inmates were analyzed. Those with and without a history of psychiatric hospitalization were compared on a range of offense characteristics, including relationship to the victim, number of victims, location of the offense, and source of firearms. Inmates with a history of hospitalization constituted 12% of all violent gun offenders and accounted for 13% of the sample's victims. They were less likely than those without a previous hospitalization to victimize strangers (odds ratio=.52) and were no more likely to commit gun violence in public or to have multiple victims. Among those with previous hospitalizations, 78% obtained guns from sources not subject to federal background checks. Of the total 1,041 victims of gun violence, only 3% were victimized by participants with a history of hospitalization who obtained guns from currently regulated sources. Prohibiting all individuals with a history of psychiatric hospitalization from purchasing firearms, absent expanded background checks, was estimated to reduce the number of gun violence victims by only 3%.

Prohibited Possessors and the Law: How Inmates in Los Angeles Jails Understand Firearm and Ammunition Regulations

Using data from 140 interviews with individuals detained in the Los Angeles County Jail system, this article examines what gun offenders know about gun and ammunition regulation in California. Though most respondents had a consistent, albeit general, understanding of the regulations limiting gun acquisition and possession, analysis suggests that their understanding of ammunition restrictions was more limited. Our sample’s awareness of firearms law is especially important to consider given that they are the very population targeted by firearms regulations and prohibitions at the local, state, and federal level. By examining what detained offenders know about firearms laws, we can better theorize about individual gaps in legal knowledge and the realistic expectations for how understanding of the law can affect behavior.

Not an ‘iron pipeline’, but many capillaries: regulating passive transactions in Los Angeles' secondary, illegal gun market

ObjectivesCalifornia has strict firearm-related laws and is exceptional in its regulation of firearms retailers. Though evidence suggests that these laws can reduce illegal access to guns, high levels of gun...

“Damned if You Do, Damned if You Don’t”

Procedural justice research generally indicates that legitimacy produces compliance when people perceive the law and legal actors to be fair. Drawing upon 140 in-depth interviews with gun offenders detained in Los Angeles County jails, this article examines legal and extra-legal factors that influence illegal gun possession. Although prior research studies on legal and illegal gun carrying have suggested a relationship between (a) safety perceptions and possession and (b) legal perceptions and possession, few have deeply interrogated how such perceptions develop and interact to inform ideas of legitimacy and compliance with gun laws. Our findings suggest that feelings of insecurity coupled with perceptions of, and experiences with, law enforcement interacted in complex ways to condition legitimacy-based beliefs, and ultimately, compliance. Although many of our respondents viewed the law as legitimate in the abstract, they believed it to be illegitimate in individual application, especially where rules and sanctions failed to account for personal experiences of insecurity.

Gun incidents at the local level: understanding the demographic variables

To maintain public safety and improve system response, a strong need exists for understanding the demographic variables associated with gun offenders and gun cases. This paper was focused on exploring these variables by creating and analyzing a weapon-related database at a local police department. The findings, although limited due to the explorative nature of the study and the quality of case files, shed some light on the personal background variables of suspects such as age, race, residence, and prior record and the weapon offenses they were involved in. The research also reveals certain challenges in developing and analyzing a gun-case database at the local level. Future researchers need to resolve these difficulties before achieving a more accurate and systematic understanding of individuals involved in gun crimes.

Overview of: “The Impact of Drug Market Pulling Levers Policing on Neighborhood Violence: An Evaluation of the High Point Drug Market Intervention”

Research Summary Pulling levers policing draws upon the focused deterrence framework, which has shown considerable promise when directed at youth, gun, and gang offenders. However, much less is known about the viability of pulling levers when applied to different contexts as well as to diverse groups of offenders. We examine the High Point (North Carolina) Drug Market Intervention (DMI), the first site to use pulling levers as a place‐based policing approach to disrupt a series of open‐air drug markets across the city. Eleven years of longitudinal data are analyzed by using difference‐in‐difference panel regression analyses combined with finite mixture estimation as a means to test for divergence in violent crime patterns. Several key, although inconsistent, findings are presented. First, we found a statistically significant reduction in violent offenses in specific high‐crime places (i.e., high‐trajectory census blocks) located across the different targeted neighborhoods compared with the remainder of High Point, and relative to comparable nontargeted areas. Second, the citywide violent crime rate actually increased after a series of interventions unfolded, which may suggest limitations with the approach. Finally, trend analyses indicated the strategy had different levels of violent crime impact throughout unique geographic contexts.Policy Implications Rather than arresting every offender identified as having participated in illicit drug trafficking across various geographic contexts within the city, officials in High Point decided to invite low‐risk drug offenders to community notification sessions in order to change their perceived risk of punishment as well as to mobilize community members across the different targeted neighborhoods. The suggestive evidence of potential, although limited, violent crime impact illustrates that this type of policing strategy may hold considerable promise. This interpretation gains credence when considered with prior evaluations of the DMI approach that illustrated the potential for reducing drug‐related crime and in light of reports of improved police–community relations. The inconsistent findings across all locations and the overall city increase in violent crime toward the end of the study period, however, raise several concerns when interpreting study results. Additionally, our findings suggest that further replications should include systematic problem‐identification, process measures, and more precise research designs.

GANGS, GUNS, AND DRUGS: RECIDIVISM AMONG SERIOUS, YOUNG OFFENDERS*

Research Summary:The primary goal of this study is to understand the factors that best explain recidivism among a sample of 322 young men aged 17 to 24 years released from prison in a Midwestern state. Specific attention is paid to the predictive validity of gang membership, gun use, and drug dependence on the timing of reconviction and the current research on desistance frames the analyses. Results from a series of proportional hazard models indicate that race, gang membership, drug dependence, and institutional behavior are critical factors in predicting the timing of reconviction. Contrary to expectations, gun use was not related to postrelease involvement in the criminal justice system.Policy Implications:Much of current violence policy has focused on the identification and enhanced prosecution of individuals deemed to be serious and chronic offenders; particular emphasis has been placed on gun offenders. The findings presented here indicate that preprison weapon involvement is not significantly associated with recidivism, likely because gun use is prevalent among young, serious offenders. Although policies aimed at the incapacitation of young, violent offenders may reduce community levels of crime in the short term, the chances for recidivism are likely to increase in the long term if factors like gang membership and drug use, and the deficits that these behaviors engender for social and emotional capital, are not addressed. More broadly, the strong, significant effect of the institutional misconduct measure signals the salience of accounting for institutional behavior when making release decisions. Institutional misconduct may be an important marker of sustained gang membership, making institutional programming and appropriate aftercare services a priority for this group of offenders.

Retrospective Accounts of Violent Events by Gun Offenders

Mills (1940) argues that there is a sharp distinction between “causes” and “explanations” or “accounts.” In this study we employ Scott and Lyman's (1968) classic formulation of accounts to examine the narrative explanations gun offenders provide for engaging in their violent acts. These narrative accounts illustrate how inmates attempt to preserve a conventional sense of self. Our observations are drawn from in-depth interviews with a random sample of Colorado inmates convicted of gun-related violent crimes. We find that inmates provide accounts in the form of justifications and excuses. Appeals to defeasibility (excuse) and denial of victim (justification) are the most common types of accounts inmates use to explain their violent behavior. We also find that inmates who report that their victim deserved the injury rarely offer additional accounts for their violence. In contrast, inmates who claim that their violent behavior was beyond their control tend to offer additional accounts in the form of justifications and excuses.

Serious Youth Gun Offenders and the Epidemic of Youth Violence in Boston

Boston, like many other major cities, experienced a sudden increase in youth homicides during the late 1980s and early 1990s. Research evidence suggests that the recent epidemic of urban youth violence was intensely concentrated among criminally active young black males residing in disadvantaged urban neighborhoods rather than all young black males residing in disadvantaged black neighborhoods. Other researchers, however, suggest that there was a diffusion of guns and gun violence from youth involved in street crack markets to youth outside the drug trade who armed themselves primarily for self-protection against the armed criminally active youth. In this paper, criminal history data are analyzed to determine whether the criminal profile of Boston arrested youth gun offenders changed over time and micro-level data on youth gun assault incidents in Boston are examined to unravel whether there were noteworthy changes in the nature of these violent events over time. The results of these analyses suggest that the youth violence epidemic in Boston was highly concentrated among serious youth gun offenders rather than a diffusion of guns away from the street drug trade, gangs, and criminally active youth.

The Unintended Consequences of Enhancing Gun Penalties: Shooting down the Commerce Clause and Arming Federal Prosecutors

To deter gun violence and punish gun offenders, Congress—like state legislatures—has repeatedly increased the penalties for illegal gun possession and the use of guns in the commission of other crimes. After several rounds of statutory increases, the penalties are now much higher than penalties for criminal conduct that accompanies gun possession and also very high relative to penalties for other serious offenses. By designating separate penalties for gun use, as high or higher than the penalties for many of the most serious traditional offenses, Congress has sent a deterrent message to would-be offenders and sought to incapacitate those who will not be deterred. Whether this message has been successful in altering the behavior of those who might otherwise commit gun offenses is an empirical question that other researchers are attempting to answer.

What we know about gun use among adolescents.

The current generation of American teenagers has grown up surrounded by gun violence. Guns have played a significant role in shaping the developmental trajectories and behaviors of many inner-city youths. In this essay, we examine the role of guns in the lives of young people, and especially in the social and symbolic construction of violent events among adolescents, primarily focusing on males. First, we review studies of gun attitudes and behaviors as well as several epidemiological studies of firearm experiences and risk factors for violence among youth. Second, we summarize several recent studies on the trends in youth violence in relation to firearms. Next, we review findings from our original research based on in-depth interviews with 377 active gun offenders from two socially isolated inner-city neighborhoods. We present descriptive counts for the sample on variables relating to gun acquisition and use. Data on the use of guns in violent events among adolescents are generally lacking in prior research. We attempt to fill that knowledge gap by presenting a summary of our more detailed analysis of gun and nongun use in violent events reported by our respondents.

Keeping Handguns From Criminal Offenders

Gun control policies must strike a balance be tween conserving legitimate use of handguns and reducing criminal use. Current federal law seeks to accomplish this ob jective by discriminating between safe and unsafe gun owners —allowing the former and prohibiting the latter from owning guns. An important practical problem soon arises: containing guns within the entitled sector. Analysis of the current supply system suggests that gun offenders acquire guns from many different sources: purchases from licensed dealers, private transfers, thefts, and black markets. Among these, legitimate purchases seem most important in supplying assaulters, and thefts seem to be the most important in supplying armed robbers. The "black market" turns out to be difficult to dis tinguish from the other sectors. To the extent it is distinct, it seems to be populated primarily by small-scale, imper manent enterprises, rather than durable firms. Analysis of how existing institutions might be deployed against this system leads to the conclusion that local enforcement capacities and federal regulatory efforts are the most important operational capacities to develop. Federal criminal investigation capa bilities are important only for limited purposes.