Types Of Firearms Research Articles

Preinjury and Event-Related Characteristics of Pediatric Firearm Injuries: The American College of Surgeons Firearm Study, United States, March 2021‒February 2022.

Objectives. To assess differences in contextual factors by intent among pediatric firearm injury patients and determine factors associated with data missingness. Methods. We retrospectively queried the American College of Surgeons Firearm Study database (March 1, 2021-February 28, 2022) for patients aged 18 years or younger. We stratified preinjury, firearm-related, and event-related factors by intent and compared them by using Fisher exact, χ2, or 1-way analysis of variance testing. Secondary analysis estimated the adjusted odds of missingness by using generalized linear modeling with binominal logit link. Results. Among 17 395 patients, 2974 (17.1%) were aged 18 years or younger; 1966 (66.1%) were injured by assault, 579 (19.5%) unintentionally, and 76 (2.6%) by self-inflicted means. Most contextual factors differed by intent, including proportion of youths with previous adverse childhood experiences, mental illness, and violent assaults or injury, firearm type and access, perpetrator relationship, and injury location. In adjusted analyses, age, trauma center designation, intent, and admission status were associated with missingness. Conclusions. Contextual factors related to pediatric firearm injury vary by intent. Specific predictors associated with missingness may inform improved future data collection. Public Health Implications. Contextual factors related to pediatric firearm injury can be obtained in a systematic manner nationally to inform targeted interventions. (Am J Public Health. 2024;114(10):1097-1109. https://doi.org/10.2105/AJPH.2024.307754).

Firearm Injuries in Children: Four-year Experience from a Rural Tertiary Care Centre of Northern India.

Firearm injuries (FAIs) continue to be a global public health problem possessing substantial emotional, physical and financial burdens on hospital resources. Although FAIs are rare in children, their incidence is gradually increasing. The aim of this study was to evaluate various aspects of FAI in children that were managed at a tertiary care centre located in the rural part of India. This clinical observational study of children <18 years of age, all due to FAI, was conducted at a tertiary care centre located in the rural part of India. Data of all children admitted with FAI over 4 years from January 2016 to December 2019 were collected. Recorded data included age, sex, motive (intentional/unintentional) and circumstances leading to injury, type and license status of firearm used, time of injury, pre-hospital care, mode of transport to hospital, duration between injury and arrival to hospital, body parts and organs injured, trauma scores, management, complications, length of hospital stay and outcomes. The recorded data were entered into a worksheet and analysed. Out of 283 cases of FAI admitted, only 24 were children with age <18 years (8.48%). The mean age was 12.66 years (male:female = 2.4:1). Sixteen were intentional (66.67%) and eight were unintentional (33.33%). The family feud was the most common reason in case of intentional FAI (43.75%), and mishandling was the most common reason in case of unintentional FAI. Country made gun was the most common firearm used (62.5%). The chest and upper back were the most common sites of injury (54.16%). Intercostal drainage tube insertion was the most common surgical procedure performed (33.33%). There were three mortalities (12.5%). The present study found that intentional FAIs in children were more common than unintentional FAIs with family feuds and mishandling being the most common causes, respectively. The unlicensed country-made gun was the most common firearm causing injury in children.

Individual, firearm, and purchasing characteristics associated with risk of firearm-related violent crime arrest: a nested case-control study

BackgroundFirearm purchasing records offer a potentially important administrative data source to identify individuals at elevated risk of perpetrating firearm violence. In this study, we describe individual, firearm, and transaction characteristics of purchasers in California who were arrested for a firearm-related violent crime (FRV) as compared to the general population of registered purchasers in the state.MethodsRelying on a dataset of all individuals with transaction records in California (1996–2021), linked to criminal records (1980–2021), we enrolled a cohort of individuals for whom we could capture the legal firearm purchase history. We identified those arrested for FRV post purchase, and using incidence density sampling, gender-matched cases to ten purchasers (controls) who remained “at risk” at the time the case was arrested. We focused on the purchase closest in time prior to the arrest (“index” purchase). We implemented conditional logistic regression and included models with controls for individual- and community-level demographics, as well as interactions between firearm and purchasing characteristics and criminal history.ResultsThe cohort included 1,212,144 individuals, of whom 6153 were arrested for FRV (0.5%). Cases were matched to 61,530 controls to form the study sample. The largest risk factor was a prior criminal history: purchasers had 5.84 times the risk of FRV if they had a prior arrest within three years of the index purchase (CI 5.44–6.27). Several transaction and firearm characteristics were also associated with FRV. For example, risk increased if the firearm was redeemed at a pawn shop (aIRR: 1.37, CI 1.05–1.77) and decreased if the transaction was a registered private party transfer (vs. retail purchase) (aIRR: 0.83, CI 0.76–0.90) or the firearm was a bolt action firearm (vs. semi-automatic) (aIRR: 0.64, CI 0.51–0.79). In the interaction models, most of the purchase and firearm features only remained significant among those with no criminal history.ConclusionsGiven limited data on firearm transactions, there has been little research on whether the type of firearm an individual purchases or the nature of the purchase might serve as indicators of risk for FRV. We found several transaction and firearm features were associated with risk of FRV. Notably, these features provided little evidence of additional risk for those with a prior criminal record.

Child Firearm-Related Homicide and Suicide by State Legislation in the US (2009-2020).

Firearms are the leading cause of death among U.S. children and adolescents. This study evaluates whether state gun laws are associated with firearm suicides and homicides in children. This is a cross-sectional database study comparing childhood firearm mortality with 36 state firearm laws using data from CDC WONDER and the RAND state firearm law database. Primary outcomes were firearm-related suicide and homicide mortalities per 100,000 persons. We examined suicide deaths by all firearms, including intentional self-harm by handguns only, intentional self-harm by rifles, shotguns, or large firearms only, and intentional self-harm by other or unspecified firearms, as well as homicide deaths for the same firearm types in each state. Welch's t-tests compared mean rates of suicide and homicide mortalities between states with and without these laws. States that either enacted or rescinded firearm legislation during this period were excluded. From 2009-2020, there were 6,735 suicides and 10,278 homicides by firearm totaling 17,013 child deaths (<18) by firearm. States with "child access prevention- negligent storage" laws demonstrated lower suicide mortality rates across all firearm types (handguns) N=13, M (mean per 100,000)=0.68, SD=0.27, p<0.001; (long guns) N=12, M=0.65, SD=0.25, p<0.001). There were no significant differences in mean suicide death rates across all firearm types when comparing states with or without firearm laws related to "minimum age youth possession", "minimum age youth purchase and sale", or "child access prevention - intentional." Comparing homicide mortality rates for all firearm types revealed no notable distinctions between states with and without the identified laws. Firearm legislation is associated with decreased suicide rates for individuals under 18, but its influence on homicides is less certain. Comprehensive research and thoughtful policy formulation are essential for addressing this pressing public health concern.

Understanding post-impact biomechanics of ballistic cranial injury by smoothed particle hydrodynamics numerical modelling

AbstractVirtual crime scene investigation using numerical models has the potential to assist in the forensic investigation of firearm-related fatalities, where ethical concerns and expensive resources limit the scope of physical experiments to comprehend the post-impact biomechanics comprehensively. The human cranial numerical model developed in this study incorporates three main components (skin, skull, and brain) with dynamic biomaterial properties. The virtual model provides valuable insights into the post-impact biomechanics of cranial ballistic injuries, particularly in high-speed events beyond conventional investigative capabilities, including the velocity of ejected blood backspatter, cavitation collapsing, and pressure waves. The validation of the numerical model, both quantitatively and qualitatively, demonstrates its ability to replicate similar bone fractures, entrance wound shapes, and backward skin ballooning observed in physical experiments of the human cranial geometry. The model also yields similar temporary cavity sizes, wound sizes, and blood backspatter time against the physical cranial model, aiding in bloodstain pattern analysis. Additionally, the numerical model enables exploration of ballistic factors that vary in each crime scene environment and influence cranial injuries, such as projectile type, velocity, impact location, and impact angle. These established injury patterns contribute to crime scene reconstruction by providing essential information on projectile trajectory, discharge distance, and firearm type, assisting in the resolution of court cases. In conclusion, the developed human cranial geometry in this study offers a reliable tool for investigating firearm-related cranial injuries, serving as a statistical reference in forensic science. Virtual crime scene investigations using these models have the potential to enhance the accuracy and efficiency of forensic analyses.

US Residents’ Recognition of Proper Use of Firearm Cable Locks

This survey study examines the ability of firearm owners and nonowners to determine correct and incorrect cable lock use across different types of firearms.

Extreme Risk Protection Orders in Connecticut, 2013-2020.

Twenty-one states and the District of Columbia have enacted Extreme Risk Protection Order (ERPO) statutes, which allow temporary removal of firearms from individuals who pose an imminent risk of harm to themselves or others. Connecticut was the first state to enact such a law in 1999. The law's implementation and use between 1999 and 2013 were previously described, finding that ERPOs were pursued rarely for the first decade and that most orders were issued in response to concerns about suicide or self-harm rather than about interpersonal violence. The current study analyzes over 1,400 ERPOs in Connecticut between 2013 and 2020 in several domains: respondent demographics, circumstances leading to ERPO filing, type of threat (suicide, violence to others, or both), number and type of firearms removed, prevalence of mental illness and drug and alcohol use, and legal outcomes. Results are similar to the earlier study, indicating that ERPO respondents in Connecticut are primarily White, male, middle-aged residents of small towns and suburbs who pose a risk of harm to themselves (67.9%) more often than to others (42.8%). Significant gender differences between ERPO respondents are discussed, as are state-specific trends over time and differences between Connecticut and other states with published ERPO data.

Pediatric Firearm Trauma on the Rise: A Retrospective Review of Over 1,100 Cases in 12 Years at One Center

BackgroundGunshot injuries are the leading cause of death among children in the United States. The goal of this study was to better understand if certain age groups, mechanisms of injury, and type of firearms were associated with the increasing rates of pediatric gun-related trauma. We hypothesized that the extremities were disproportionately targeted when compared with the random likelihood of striking specific body-surface areas. MethodsThis study includes pediatric firearm-related injury (FRI) patients who presented to a single free-standing level 1 pediatric hospital or died at the scene from 2010 to 2021. The hospital data was collected prospectively as part of a level 1 trauma system electronic database. Death data was collected from the local coroner's office. ResultsBetween 2010 and 2021, 1,126 pediatric FRI occurred in the geographic region studied. Demographic information available for 1,118 patients showed that 897 (80.23%) were male, and that black individuals had a statistically significant increased rate of FRI compared with white or Hispanic individuals. Mean age was 13.69 years. Most injuries were caused by handguns. ConclusionsThis data could help leaders design strategies to combat the violence, such as legislation that limits handgun access to all, especially children, and mandates safe storage of handguns. Gun-lock programs, universal background checks, and firearm-ownership education also might help stem this tide of violence. Level of EvidenceLevel II Prognosis study.

The Jarring Reality: Adolescent and Pediatric Gunshot Trauma on the Rise in a Major Urban Institution.

Firearms are the leading cause of death in the pediatric population, and the incidence of firearm injury is on the rise in the United States. The purpose of this study was to examine the incidence of pediatric gunshot wounds (GSWs) in New Orleans from 2012 to 2023 and evaluate factors that contribute to mortality. A retrospective analysis of pediatric GSWs was conducted using the trauma database at a Level I trauma center in New Orleans, Louisiana. All patients aged 0 to 18 years with a GSW between January 1, 2012, and January 1, 2023, were evaluated. Demographic data, Injury Severity Score (ISS), hospital length of stay (LOS), discharge disposition, intent of injury, mortality, firearm type, orthopaedic injuries, and related surgical procedures were extracted from the database. Linear regression was used to assess the trend of GSWs over time, and logistic regression was used to identify variables that predicted mortality. Statistical significance was defined as α = 0.05. Geographic information system (GIS) mapping was conducted using the ZIP code location of injury to identify geographic areas with the greatest number of GSWs. A significant increasing trend was observed in the number of pediatric GSWs when adjusted for changes in population ( P = 0.014), and the number of GSWs increased 43.2% over the duration of the study. Higher ISS, shorter length of stay, and self-inflicted intent of injury were notable predictors of mortality. Three hundred fifty-four patients (31.4%) had at least one orthopaedic injury, and of the survivors, 365 patients (35.6%) required at least one surgical procedure in the operating room during their admission. The number of GSWs in the pediatric population in New Orleans presenting at a large level 1 trauma center demonstrated a statistically significant increasing trend over the past 11 years. ISS and self-inflicted intent were predictive of mortality within this pediatric patient population.

Suicide by Gunshot Wound to the Posterior Head and Neck: A Retrospective Case Series and Review of the Literature.

Suicide by firearm is a significant public health concern in specific regions of the world. Depending on firearm availability, any type of firearm may be used, including handguns, shotguns, and long rifles. Common entrance wound sites in suicidal gunshot wounds include the head, with classic gunshot wound locations including the temple, the forehead, the submental aspect of the chin, and inside the mouth. Occasionally, suicidal gunshot wounds occur in atypical body locations such as the back of the head and neck. Given their relative rarity, suicidal gunshot wounds in these regions may be mistaken for homicides. In this report, we present 5 cases of suicidal gunshot wounds to the back of the head and/or neck. In our series, we focus on differentiating each case from homicides involving gunshot wounds in similar areas of the head and neck.

Ghost guns and crime: a tale of two California cities

BackgroundPrivately made firearms (PMFs) or “ghost guns” are homemade, unserialized, untraceable firearms that have been increasingly used in violent crime in the United States. Very little is known about the types of PMFs recovered by law enforcement agencies and the crimes associated with these recoveries. This lack of information limits effective violence prevention policies and practices. Comparative analysis of PMF recoveries in specific cities helps clarify whether local PMF patterns and characteristics vary or reflect more general trends. This research advances epidemiological understanding of emergent violent gun injury prevention challenges by identifying variations in recovered PMF types and use in violent, drug, and weapon-related offenses in Los Angeles and San Diego, California.MethodsConjunctive analysis of case configurations (CACC) identifies patterns among observations (i.e., case configurations) and calculates their probability associated with a given outcome. CACC was used to identify the most common types of PMFs recovered by the Los Angeles (LAPD) and San Diego (SDPD) police departments. For each department and offense type, case configurations with above-average probabilities of offense involvement were determined. Comparisons across departments were made to identify similarities and differences in PMF characteristics and usage.ResultsPMFs were more likely to be involved in violent and weapon-related offenses in Los Angles but more likely to be involved in drug-related offenses in San Diego. In both cities, the 9 mm Polymer 80 handgun was the dominant PMF. However, 9 mm handguns were most likely to be involved in weapon-related offenses in Los Angeles compared to 0.40 handguns in San Diego. Furthermore, large-caliber handguns tended to display above-average probabilities of involvement in violent and drug offenses in Los Angeles. Long guns were represented in case configurations with above-average probabilities of involvement in substantive crimes, including violence.ConclusionsComparative analyses of PMF recovery patterns in Los Angeles and San Diego reveal meaningful contextual variations in PMF characteristics and suggest intentional firearm type selections by offenders. The results support increased regulation of PMFs and highlight the importance of efforts to identify and disrupt the illicit supply of large-caliber PMF handguns and PMF long guns.

Measuring the Market for Legal Firearms

The Massachusetts Firearms Records Bureau recently published administrative data covering the universe of legal firearm transactions in the state. We use these data to validate state-level background checks as a proxy for firearm transactions and show that historical trends in transactions within Massachusetts align with the rest of the United States. Using auxiliary data from a national survey, we show that the Massachusetts dataset can detect patterns in the demographics of both gun ownership and type of firearm purchased. Our analysis suggests that this dataset is a promising source of information for studying interactions in the market for legal firearms.

Comparison of In-Hospital Mortality and Neurosurgical Intervention Between Intracranial Gunshot Wounds Arising From Long Guns and Handguns: A Propensity Score Matched Study.

Patients with intracranial gunshot wounds (IC-GSWs) often present with severe neurological injuries requiring prompt neurological evaluation. Neurosurgical intervention is reserved for those with reasonable chances of survival. Handguns and long guns, such as shotguns and rifles, have differing mechanisms of injury which may influence surgical candidacy and outcomes. This study aims to compare rates and types of neurosurgical intervention and inpatient outcomes in patients with IC-GSWs handguns and long guns. The National Trauma Data Bank was retrospectively queried for patients with IC-GSWs from 2017 to 2019. Patients with long gun IC-GSWs were propensity score matched with those with handgun IC-GSWs based on patient demographics, comorbidities, insurance status, injury extent and severity, and hospital trauma level. Group differences were compared using Student's t-tests and Pearson's χ2 tests, and multivariable logistic regression was used to identify predictors of in-hospital mortality. Overall, patients in the long gun group were more likely to undergo neurosurgical intervention (21% vs 17%, P = .02). Following propensity score matching, the long gun group had lower rates of in-hospital mortality (35% vs 43%, P < .01), lower rates of cardiac arrest (5% vs 8%, P = .02), and lower rates of reoperation (0% vs 2%, P = .02) than the handgun group. In multivariable regression, independent predictors of survival included long gun IC-GSWs (odds ratio [OR] 0.65, CI 0.52-0.83), neurosurgical foreign body removal (OR 0.44, CI 0.33-0.58), intracranial debridement (OR 0.47, 0.33-0.67), and craniectomy (OR 0.46, CI 0.34-0.63). Patients with IC-GSWs present to the hospital with severe neurological injury. Neurosurgical intervention was independently associated with decreased mortality. After matching, patients with long gun IC-GSWs experienced lower in-hospital mortality rates compared with those from handguns. This study suggests that patients suffering from long gun IC-GSW may respond particularly well to neurosurgical intervention and firearm type should be considered when determining neurosurgical candidacy.

Gunshot residue (GSR): Frequency of residue types encountered in case work and background levels on control samples

The evaluation of criminal cases involving the discharge of a firearm requires reliable and up to date information regarding the transfer and persistence of gunshot residue (GSR). Similarly, knowledge of background levels of GSR on relevant populations and awareness of the potential for contamination/secondary transfer is essential. In this paper we build on previous work published by this laboratory and provide an update on the frequency of gunshot residue types in discharged cartridge casings (DCC) encountered in casework within the Republic of Ireland. In conjunction, an examination of the types of firearms encountered in casework and the associated residue types is undertaken. Finally, a review of levels of GSR particles detected on control samples taken from members of An Garda Síochána, the Irish police is detailed. Control samples are taken before a police officer samples a detainee suspected of involvement in an incident where a firearm was discharged and/or subsequently handled.

Firearm Ownership and Support for Political Violence in the United States

Little is known about support for and willingness to engage in political violence in the United States. Such violence would likely involve firearms. To evaluate whether firearm owners' and nonowners' support for political violence differs and whether support among owners varies by type of firearms owned, recency of purchase, and frequency of carrying a loaded firearm in public. This cross-sectional nationally representative survey study was conducted from May 13 to June 2, 2022, among US adult members of the Ipsos KnowledgePanel, including an oversample of firearm owners. Firearm ownership vs nonownership. Main outcomes concern (1) support for political violence, in general and to advance specific political objectives; (2) personal willingness to engage in political violence, by severity of violence and target population; and (3) perceived likelihood of firearm use in political violence. Outcomes are expressed as weighted proportions and adjusted prevalence differences, with P values adjusted for the false-discovery rate and reported as q values. The analytic sample comprised 12 851 respondents: 5820 (45.3%) firearm owners, 6132 (47.7%) nonowners without firearms at home, and 899 (7.0%) nonowners with firearms at home. After weighting, 51.0% (95% CI, 49.9%-52.1%) were female, 8.5% (95% CI, 7.5%-9.5%) Hispanic, 9.1% (95% CI, 8.1%-10.2%) non-Hispanic Black, and 62.6% (95% CI, 61.5%-63.8%) non-Hispanic White; the mean (SD) age was 48.5 (18.0) years. Owners were more likely than nonowners without firearms at home to consider violence usually or always justified to advance at least 1 of 17 specific political objectives (owners: 38.8%; 95% CI, 37.3%-40.4%; nonowners: 29.8%; 95% CI, 28.5%-31.2%; adjusted difference, 6.5 percentage points; 95% CI, 4.5-9.3 percentage points; q < .001) but were not more willing to engage in political violence. Recent purchasers, owners who always or nearly always carry loaded firearms in public, and to a lesser extent, owners of assault-type rifles were more supportive of and willing to engage in political violence than other subgroups of firearm owners. In this study of support for political violence in the United States, differences between firearm owners and nonowners without firearms at home were small to moderate when present. Differences were greater among subsets of owners than between owners and nonowners. These findings can guide risk-based prevention efforts.

The use of machine learning for the determination of a type/model of firearms by the characteristics on cartridge cases

Cartridge cases are commonly collected at crime scenes involving firearms. One of the stages in forensic examination is the determination of the type and model of firearms based on the class characteristics of these cartridge cases. A firearm examiner evaluates the class characteristics on the basis of their knowledge and experience, and by referring to collections of cartridge cases representing class characteristics of different firearms, special databases and reference books. However, this process is highly subjective. The novelty of this research is in developing objective methods of firearms determination by applying a machine learning approach. In this study, several Convolutional Neural Networks from Keras programming package were trained to determine the type/model of a firearm based on the class characteristics observed on cartridge cases from seven different categories of firearms. The prediction accuracies received by this method range from 71 to 81 percent for models based on different Convolutional Neural Networks, while using an ensemble of the machine learning models increased the accuracy to 88 %. The research demonstrates the efficacy of machine learning in enhancing accuracy and reducing subjectivity in firearm identification, highlighting its significant potential in forensic science applications.

251 A Comparison of Neurosurgical Intervention and In-hospital Mortality in Patients With Intracranial Gunshot Wounds From Long Guns Versus Handguns: A Propensity-matched National Database Analysis

INTRODUCTION: Intracranial gunshot wounds (IC-GSW) are an understudied cause of mortality with indications for neurosurgical intervention. Historically, handguns have accounted for the majority of IC-GSW, but incidents involving long guns (rifles/shotguns) are rising. A comparison of neurosurgical intervention and in-hospital mortality by firearm type has yet to be fully explored. METHODS: The National Trauma Data Bank was queried from 2017-2019 for patients with IC-GSW presenting to a hospital with signs of life. Propensity score matching was performed between LG and HG groups based on demographics, comorbidities, Glasgow Coma Scale (GCS), and insurance type. Group differences were compared using paired Student’s t-tests and Pearson’s chi-square tests. A logistic regression model was developed to identify predictors of mortality. RESULTS: A total of 6,585 patients met inclusion criteria. Following one-to-one propensity score matching, 510 patients were identified and compared in each group. Seventy percent of patients with IC-GSW arrived with a GCS &lt; 8 (68.43% LG vs. 72.16% HG, p=0.19). Rates of neurosurgical intervention were similar between the LG and HG groups (20.49% vs. 23.53%, p = 0.26), however LG patients had a lower rate of in-hospital mortality (34.51% vs. 42.55%, p &lt; 0.01). Neurosurgical wound debridement (OR = 0.46, p&lt;0.001), foreign body removal (OR = 0.44, p &lt; 0.001), craniectomy (OR = 0.48, p &lt; 0.001), and ventriculostomy (OR = 0.58, p &lt; 0.01) were associated with lower odds of mortality. CONCLUSIONS: Patients with IC-GSW often present to the hospital in critical neurologic condition. Neurosurgical intervention is associated with lower odds of in-hospital mortality. Though both groups undergo neurosurgery at similar rates, patients with LG IC-GSW have a lower mortality rate. This study identifies a subset of patients who may particularly benefit from neurosurgery. Further research is needed to quantify the rationale behind these findings.

Adversarial attack against deep learning algorithms for gun category detection

Contemporarily, many deep learning methods have been generated for weapon detection. The weapon detection technology could be used in investigating violent cases. However, the existing gun detection models lack adversarial attack verification for special types of firearms and special picture samples. This study investigates the efficiency of Fast Gradient Sign Method(FGSM) adversarial attack in the field of weapon detection and the influence of weapon category on the attacks result. The dataset is scraped from IMDBF.com and the model being attacked is MobileNetV2, created by HeeebsInc in 2020. As a result, using FGSM methods, adversarial samples generated in film and television graphics containing pistols and rifles can effectively decrease the accuracy of the weapon detection model above. Besides, it is observed the difference of eps needed in attacking different types of gun graphics like film pictures and collection photos. These results verify that some weapon detection models have weak anti-interference, which may provide some ideas for future attacks like BIM or PGD attack.

Chemical analysis of polymers used for 3D printing of firearms

3D-printed firearms cause challenges in criminal investigations and forensic analysis because they are difficult to trace. Indeed, in addition to being "ghost guns", they may not produce all the conventional ballistic traces normally used for firearm identification. However, 3D-printed firearms produce other very specific traces, such as polymer traces which come from the polymers used to print the firearm. To date, only a few studies have focused on the analysis of polymer traces. This study therefore aims to characterize polymer traces from 3D-printed firearms, using non-destructive spectroscopic techniques readily available in most forensic laboratories (i.e., FTIR and Raman) and evaluate the potential for association of polymer specimens or traces with their source. To do so, the study was divided into four parts. First, the population study conducted among 3D printing companies and individuals practicing 3D printing has revealed that PLA and PLA+ are the most widely used polymer types in Quebec, Canada. Second, FTIR and Raman spectroscopic analysis of polymer samples collected during the population study has allowed the development of a reference polymer spectral database. The analysis and interpretation of these spectra revealed that polymer filaments present very low intravariability, but very high intervariability, due in part to the different polymer types and the pigments used to color them. The use of chemometric tools with the spectra showed that these two spectroscopic methods were highly discriminating. Third, test firing of 3D-printed firearms has allowed for the simulation of a scene involving this type of firearm and the collection of polymer traces generated. Fourth, the comparison of chemical signatures between polymer filaments and polymer traces has allowed for the evaluation of the potential for chemical association. This study highlights the added value of chemical analysis of 3D-printed firearms polymer traces in a criminal investigation by demonstrating that polymer filaments, the polymer from which a 3D-printed firearm is made, as well as polymer traces generated during firing, can be linked chemically and provide relevant information.

Defining the Problem: 53 Years of Firearm Violence Afflicting America's Schools.

Firearm violence and school shootings remain a significant public health problem. This study aimed to examine how publicly available data from all 50 states might improve our understanding of the situation, firearm type, and demographics surrounding school shootings. School shootings occurring in the US for 53 years ending in May 2022 were analyzed, using primary data files that were obtained from the Center for Homeland Defense and Security. Data analyzed included situation, injury, firearm type, and demographics of victims and shooters. We compared the ratio of fatalities per wounded after stratifying by type of weapon. Rates (among children) of school shooting victims, wounded, and fatalities per 1 million population were stratified by year and compared over time. A total of 2,056 school shooting incidents involving 3,083 victims were analyzed: 2,033 children, 5 to 17 years, and 1,050 adults, 18 to 74 years. Most victims (77%) and shooters (96%) were male individuals with a mean age of 18 and 19 years, respectively. Of the weapons identified, handguns, rifles, and shotguns accounted for 84%, 7%, and 4%, respectively. Rifles had a higher fatality-to-wounded ratio (0.45) compared with shooters using multiple weapons (0.41), handguns (0.35), and shotguns (0.30). Linear regression analysis identified a significant increase in the rate of school shooting victims (β = 0.02, p = 0.0003), wounded (β = 0.01, p = 0.026), and fatalities (β = 0.01, p = 0.0003) among children over time. Despite heightened public awareness, the incidence of school shooting victims, wounded, and fatalities among children has steadily and significantly increased over the past 53 years. Understanding the epidemic represents the first step in preventing continued firearm violence in our schools.