Welcome to NIJ’s Term of the Month. Each month we are featuring a term from our scientific research portfolios informing significant American justice system issues and solutions.
January 2023 - Risk Terrain Modeling
Risk terrain modeling is a science-based method of identifying and measuring crime risk posed by the features of a specific physical location — for example, a parking lot, a convenience store, a bar, or a vacant building.
Risk terrain modeling is a tool designed to diagnose crime location patterns. Risk terrain modeling software generates an overall crime risk value for specific locations and explains which terrain features contribute to crime risk.
Assigning a risk value to each characteristic of a location allows public agencies to isolate those characteristics, or combinations of characteristics, that most influence crime.
Two important advantages of risk terrain modeling, in comparison to other proactive policing methods, are:
- Scope of resource response to locations at risk: By identifying the characteristics of a place associated with increased risk of crime, risk terrain modeling creates opportunities for comprehensive responses not limited to law enforcement action. For example, if poor lighting is found to elevate crime risk, then the streets department could be asked to improve it.
- Fourth Amendment protection from unreasonable search and seizure: Risk terrain modeling focuses on attributes of a place, not of a person. Thus, the use of risk terrain modeling to guide officer actions generally may be less likely than other proactive policing methods to be associated with a risk of constitutional rights violations.
By pinpointing crime risk associated with specific places on a map, risk terrain modeling can help guide geographic distribution of law enforcement and other public resources.
Research on the application of risk terrain modeling in multiple communities has found it to be an effective and accurate method of identifying crime risk and altering the characteristics of a place to prevent crime problems.
- Risk Terrain Modeling for Spatial Risk Analysis
- Innovative Methodologies for Assessing Radicalization Risk: Risk Terrain Modeling and Conjunctive Analysis
- Facilitators and Impediments to Designing, Implementing, and Evaluating Risk-Based Policing Strategies Using Risk Terrain Modeling: Insights From a Multi-City Evaluation in the United States
- Systematic Review and Meta‑Analysis of Risk Terrain Modelling (RTM) as a Spatial Forecasting Method
- Risk Terrain Modeling Works
- Evidence-Based Practices and Strategies: Risk Terrain Modeling
Expungement is the process by which a record of criminal conviction is destroyed or sealed from state or federal record. An expungement treats the conviction as if it had never happened, removing it from an individual’s criminal record and, ideally, the public record. However, in the digital age, completely removing any information in the public record has become challenging.
Most expungement proceedings take place in state courts. Each state has its own distinct laws about who is eligible for expungement, which offenses can be expunged, and how records will be managed. Some states have “clean slate” laws that require the state government to automatically expunge minor criminal records for qualifying individuals. Other states require individuals to petition the court to clear part or all of a criminal record.
An individual’s criminal record can create significant reentry barriers. For example, a record can thwart efforts to secure housing or gain employment. Expunging an individual’s criminal record, where appropriate, can be critical to their ability to move forward and live a law-abiding life.
It is important to note that an expungement is not the same as “forgiveness” for committing a crime — that is known as a legal pardon.
A black box study design can be used to measure the overall behavior of a complex system. It disregards the internal processes and simply measures how the final output changes depending on the input. Black box testing has long been used to study complex systems in software engineering, physics, and psychology.
In the forensic sciences, researchers use black box studies to measure the accuracy and reliability of forensic disciplines as they are currently practiced. This includes latent fingerprint examination, bloodstain pattern analysis, forensic firearms examination, and others. These disciplines largely depend on subjective comparison of evidence by human experts. The researcher uses a set of samples with known “ground truth” and treats the examiner as a black box, measuring how often their conclusions are right or wrong. This is important information for the courts to consider when deciding whether to admit forensic testimony.
Conversely, a “white box” study — in the context of forensic science — looks at the details of the examiner’s thought process or methodology to determine which factors have the most effect on the outcome. It allows the researcher to look inside the black box and gain insight into how and why examiners reach their conclusions.
Read an NIJ Journal article on the history and legacy of an influential black box study examining the accuracy and reliability of latent fingerprint examination. Results from a black-box study for digital examiners by the National Institute of Standards and Technology.
Subadult is a categorization used by anthropologists, including forensic anthropologists, to define human skeletal remains believed to be from a person whose age-at-death was 20 or younger. Investigators traditionally have used pelvic differences between males and females and the predictable development of teeth to try to determine the sex and age of skeletal remains of infants, children, and adolescents, but that information is often insufficient to make an accurate determination.
Investigators also look at long bone lengths (femur and tibia, for example) and the fusion growth plates in bones (epiphyseal fusion) to determine age-at-death, but those indicators are only useful during specific periods of a person’s growth and, without a large database for comparison, individual measurements are limited in what they can reveal.
New research is expanding the markers scientists can use to include spinal canal measurements, cranial shape and form measurements, and detailed measurements of the shape and form of teeth. This research, when combined with growing databases of subadult skeletons, is allowing investigators to consider a wide range of markers for determining age and sex, as well as population affinity (ethnicity).
Increasing the number of markers is important because they change significantly as a subadult grows from infancy through adolescence, and the presence or absence of a marker can narrow the age range.
- Meeting the Forensic Challenges of Subadult Skeletons (article)
- Subadult Ancestry Estimation Using Craniometrics, Macromorphoscopics, Odontometrics, and Dental Morphology (NIJ grant)
- Development of Modern Subadult Standards: Improved Age and Sex Estimation in U.S. Forensic Practice (NIJ grant)
- Developing Subadult Sex Estimation Standards Using Adult Morphological Sex Traits and an Ontogenetic Approach (NIJ grant)
- The Subadult Virtual Anthropology Database (SVAD): An Accessible Repository of Contemporary Subadult Reference Data (article, Forensic Sciences, 2022)
Virtual comparison microscopy is the use of high-resolution 3D surface scanning and measurement in the field of firearm and tool mark analysis. The accurate surface imaging of bullets and shell casings with 3D visualization tools and advanced algorithms allow forensic examiners to view, annotate, conduct blind verification, and develop a statistical basis for identifying and matching ballistics evidence.
With a virtual comparison microscopy system, the bullets and casings are scanned, creating a detailed topographical map that can be shared between crime labs. The electronic file allows for the verification of findings by a second examiner. The traditional 2D comparison method requires the actual evidence — spent bullets or shell casings — to be examined directly.
Because virtual comparison microscopy files can be easily shared, they allow for better training, error-rate studies, and proficiency testing in crime labs. Although researchers expect human examiners to conduct ballistics testing for the foreseeable future, as the database of bullets, casings, and guns grows, sophisticated algorithms and machine learning could allow computers to play a significant role.
Select Resources and Funded Awards:
- A Century of Ballistics Comparison Giving Way to Virtual 3D Methods (Article)
- Evaluation of 3D Virtual Comparison Microscopy for Firearm Forensics within the Crime Lab
- Expanding the Scope and Efficiency of 3D Surface Topography Analysis in Firearm Forensics
- Assessing Class Consistency and Common Source Using 3D Virtual Comparison Microscopy in Firearm Forensics
- Additional NIJ funded research on Virtual Comparison Microscopy
A student threat assessment is a systematic approach to evaluating the likelihood that a student will carry out a violent act after an expressed threat or threatening behaviors.
Threat assessments are performed by interdisciplinary school-based teams. The teams can give schools a proactive, effective alternative to reactive disciplinary practices such as zero tolerance discipline and exclusionary discipline such as student suspensions.
Threat assessments can prove challenging, however. Schools must substantiate information received in threat assessments, and threat assessments will not be a practical means of assessing all tips related to threatened school violence.
- Student Threat Assessment as a Safe and Supportive Prevention Strategy
- School Safety: Research on Gathering Tips and Addressing Threats
- Threat Assessment and Reporting
- Threat Assessment as a School Violence Prevention Strategy
- Preparing for and Responding to Threats and Violence - Breakout Session, NIJ Virtual Conference on School Safety
Deradicalization refers to an individual’s or group’s disavowal of, or shift away from, extremist beliefs that can support terrorism. The term can also refer to policies, practices, or strategies designed to advance a deradicalization process. Deradicalization is one element of a comprehensive approach to preventing extremist violence.
NIJ continues to support research on deradicalization and related topics. A 2022 NIJ research solicitation called for “research to better understand the deradicalization and disengagement phenomena. NIJ is particularly interested in understanding factors that promote withdrawal and independence from extremist behaviors, as well as those factors that play a role in encouraging individuals to depart radical ideologies (or at least shift away to less-extreme beliefs).”
Microbial forensics is the investigation of the cloud of biological evidence humans leave behind at crime scenes that includes bacteria, fungi, viruses, and other microbial evidence. Researchers have learned over the past 20 years that each person carries a distinct microbial signature that is shed into the environment and left on objects that are touched. The number of microbes in the biological clouds that surround each of us is enormous, but because they are invisible to the eye, we are unaware of them.
The microbial communities living in association with the human body make up an individual’s microbiome, and the bacteria alone are typically 10 times more prevalent on a body than human cells. About 3% of a person’s body mass is made up of microbes.
The birth of microbial forensics came with the 2001 attacks in Washington, D.C. using anthrax spores. The efforts to identify the strain of anthrax established microbial forensics as an investigative tool, and since that time it has been used to detect microbial traces on phones, doorknobs, keyboards, and other objects a suspect may have touched. In the future a microbial signature may reveal details about a person’s diet, health, and drug use.
- The Search for a Microbial Death Clock (article)
- The Forensic Microbiome: The Invisible Traces We Leave Behind (article)
- The Evidence We Leave Behind: Part 1 (podcast)
- The Evidence We Leave Behind: Part 2 (podcast) available on June 6 from NIJ’s podcast page.
- NIJ Microbiome Grants
Unmanned aircraft systems is a term that encompasses not only the unmanned aircraft vehicle but also the flight controller on the ground, and the system of communication between the two. Under FAA Part 107, unmanned aircraft vehicles are air vehicles weighing between a half and 55 pounds that operate by remote pilot and are often fitted with specialized cameras, GPS, and/or other sensors that collect and often relay information via a communications link to a variety of destinations, including the remote pilot and/or a command center. In law enforcement, unmanned aircraft systems are used in a variety of ways, including crowd control, traffic and accident reporting, search and rescue, crime scene reconstruction, pre-operational situational awareness to optimize officer and individual safety (e.g. by gathering information for bomb threats and hostage situations), and even as first responders.
Unmanned aircraft systems are subject to the rules set forth by the Federal Aviation Administration to maintain safe national airspace, specifically Unmanned Aircraft Rules (Part 107). Since unmanned aircraft systems also are operated from a remote command and control center and relay information, equipment must be certified by the Federal Communications Commission to minimize harmful radio interference. Most unmanned aircraft system pilots are required to maintain visual-line-of-sight (VLOS) with their aircrafts, with the exception of those who have beyond-visual-line-of-sight (BVLOS) certification.
- Detecting and Processing Clandestine Human Remains with Unmanned Aerial Systems and Multispectral Remote Sensing (Grant)
- Unmanned Aircraft Systems Can Support Law Enforcement in Crash Scene Reconstruction (Article)
- Evaluation of Terrestrial and Aerial Remote Sensing with Small Unmanned Aircraft Systems (SUAS) for Forensic Crime-Scene Reconstruction (Grant)
- Evaluating Aerial Systems for Crime-Scene Reconstruction (Article)
- A Comparison of Small Unmanned Aircraft System (SUAS) Aerial and Terrestrial Methods for Accident Scene Investigation Information Collection (Grant)
- How Law Enforcement Can Harness the Benefits of an Unmanned Aircraft Systems (UAS) Program (Article)
Community corrections is a term for managing individuals convicted of a crime and serving their sentences in a community setting, rather than in prison or jail. Community supervision is another term for community corrections. Probation and parole are two primary forms of community corrections. Community supervision may also be ordered for individuals awaiting trial.
Probation is an alternative to jail, or sometimes prison, ordered when the sentencing court decides that the crime does not warrant incarceration. Probation officers supervise individuals on probation, monitoring their activities and ensuring compliance with conditions of supervision. Conditions of supervision include avoidance of crime and association with individuals with felony sentences and may include school attendance, employment, testing for drugs or alcohol, or other milestones to be met by the sentenced individual.
Parole is supervised release from prison after a portion of a sentence has been served. Parole is granted when a parole board or other authorized public body determines that release of an individual from confinement is justified in light of evidence of rehabilitation and public safety interests. Persons on parole, like those on probation, regularly meet with supervision officers and satisfy conditions of parole to complete their sentence.
The philosophy underlying community corrections is to prevent criminal behavior through close supervision and the imposition of restrictions on probation or parole in an environment designed to be more conducive to rehabilitation while maintaining public safety. A related goal of community corrections is the reduction of overcrowding of prisons and jails.
- Community Corrections, NIJ.gov Topic page with article listings.
- “Tapping into Artificial Intelligence: Advanced Technology to Prevent Crime and Support Reentry,” by Eric Martin and Angela Moore, NIJ.gov, August 6, 2020. NIJ.gov. This article originally appeared in the June/July 2020 issue of Corrections Today, as submitted by the National Institute of Justice. It was reprinted with permission of the American Correctional Association.
- “The Role of Human Service Providers During Community Supervision,” by Cecelia Klingele, National Institute of Justice, NIJ.gov, September 2021.
- “Crime and Desistance: Probing How Probationers' Thoughts on Crime May Inform Their Conduct,” July 20, 2021, NIJ.gov article based upon the research report “Research on Offender Decision-Making and Desistance From Crime: A Multi-Theory Assessment of Offender Cognition Change.” Principal Investigator: Caleb D. Lloyd. The research was funded by NIJ award 2014-R2-CX-0009, awarded to The University of Texas at El Paso.
- “The NIJ Recidivism Forecasting Challenge: Contextualizing the Results,” by Veronica White, D. Michael Applegarth, Joel Hunt, and Caleb Hudgins, National Institute of Justice, February 2022.
- Community corrections programs and practices rated by NIJ’s CrimeSolutions.
Situational crime prevention (SCP) is a crime reduction strategy used by law enforcement that stemmed from the analysis of circumstances that give rise to particular types of crime. SCP posits that criminal acts may be deterred by strategic environmental or managerial changes. It differs from other crime prevention strategies because it focuses on the setting for crime, rather than those committing criminal acts. The main goal of situational crime prevention is to make criminal acts less attractive to people who might potentially offend.
There are a multitude of ways this can be accomplished, including increasing the risk and reducing the reward of committing a crime, removing the target, increasing surveillance, controlling weapons, and alerting the offending person’s conscience. As such, it requires assistance from the leadership at a number of public and private locations that tend to attract crime, including schools, hospitals, parks, bars, stores, and transit.
- Understanding the Causes of School Violence Using Open Source Data
- Evaluation of a Situational Crime Prevention Approach in Three Jails: The Jail Sexual Assault Prevention Project
- Understanding the Causes of School Violence Using Open Source Data
- Situational Approaches to Making Communities and Correction Institutions Safer
There also are promising practices related to situational crime prevention on CrimeSolutions:
- Closed Circuit Television (CCTV) Surveillance
- Improved Street Lighting
- Metal Detectors and Security Screenings at Airports as a Counterterrorism Strategy
- Alley Gating in the United Kingdom
NIJ continues to fund research with the goals of understanding the effects and usefulness of situational crime prevention. Ongoing research projects include:
A major theory in socio-behavioral and other sciences, life course theory posits that individual life experience is connected to dynamics that are driven by historical and socioeconomical factors.
In the criminological context, the central idea of life course theory is that childhood antisocial behavior, adolescent delinquency, and early adult criminal infractions are more likely when an individual's bond to society is weak or broken. It stresses turning points that may occur over an individual’s life course which affect their connection to society and its institutions, levels of social control, and thus likelihood to become involved in criminal behavior.
The theory is an effort to offer a comprehensive outlook on the study of criminal activity by considering a multitude of factors that affect offending across different time periods and contexts. The goal is to explain the onset of, persistence of, and desistance from offending behavior over the life course of an individual.
The Trafficking Victims Protection Act (TVPA) of 2000 was the first Federal law to address the trafficking of persons, aimed at the prevention, protection, and prosecution of both labor trafficking and sex trafficking. The TVPA created the most widely accepted definition of labor trafficking: "the recruitment, harboring, transportation, provision, or obtaining of a person for labor or services, through the use of force, fraud, or coercion for the purpose of subjection to involuntary servitude, peonage, debt bondage, or slavery” (DHS Human Trafficking Laws & Regulations).
Per the National Action Plan to Combat Human Trafficking, “Labor trafficking occurs across many different industries, including domestic work, traveling sales crews, food services, peddling and begging, agriculture, health and beauty services, construction, hospitality, and landscaping.”
- Article: How Does Labor Trafficking Occur in U.S. Communities and What Becomes of the Victims?
- Article: The Prevalence of Labor Trafficking in the United States
- Podcast: Human and Labor Trafficking in the U.S.
- Data-collection: Human Trafficking Reporting System
- Report: Prosecuting Human Trafficking Cases: Lessons Learned and Promising Practices
- Report: Understanding the Organization, Operation and Victimization of Labor Trafficking in the United States
- Report: An Exploratory Study of Labor Trafficking Among U.S. Citizen Victims
NIJ continues to fund research with the goals of understanding and preventing labor trafficking. Select ongoing research projects:
- Understanding the Trafficking of Children for the Purpose of Labor in the United States
- Evaluating the OHTS Tool and Assessing Outcomes for Human Trafficking Survivors
- Labor trafficking in construction and hospitality: Analyzing victim recruitment, exploitation, and service needs to identify strategies for prevention and intervention
- Understanding What Works in the Successful Identification, Investigation, and Prosecution of Labor Trafficking Cases in the United States
Machine learning is the study of computer algorithms that improve automatically through experience. It refers to the development of systems that can learn from data. A machine learning algorithm can, after exposure to an initial set of data, evaluate new, previously unseen examples and relate them to the initial “training” data. It is ideally suited for classification problems that involve implicit patterns, and it is most effective when used in conjunction with large amounts of data.
Criminal justice applications of machine learning include detecting patterns and anomalous behavior, predicting crowd behavior and crime patterns, protecting critical infrastructure, and uncovering criminal networks.
Read an NIJ Journal article on the role of machine learning in criminal justice.
Desistance is generally understood to mean the reduction in criminal behavior over time. It is the process of individuals ceasing engagement in criminal activities. Varying definitions and measurement strategies have evolved over the years. Early scholarship tended to view desistance as a discrete event — that is, the termination of offending or end of a criminal career. More recent definitions, however, suggest that desistance is instead a developmental process by which criminality declines over time.
In NIJ’s new publication Desistance From Crime: Implications for Research, Policy, and Practice, Dr. Michael Rocque offers an updated, theoretically grounded definition as a foundation for future work: Desistance is “the process by which criminality, or the individual risk for antisocial conduct, declines over the life-course, generally after adolescence.”
- Links to each chapter in Desistance From Crime: Implications for Research, Policy, and Practice
- NIJ hosted a webinar during which the authors presented and discussed key themes from each of their chapters. Watch a recording of the webinar.
Historically called domestic violence, intimate partner violence describes physical, sexual, or psychological harm by a current or former intimate partner or spouse. Types of intimate partner violence include physical violence, sexual violence, threats of physical or sexual violence, psychological/emotional violence, and stalking.
Violence by an intimate partner is linked to both immediate and long-term health, social, and economic consequences. Factors at all levels — individual, relationship, community, and societal — contribute to intimate partner violence. This type of violence can occur among heterosexual or same-sex couples.
Preventing intimate partner violence requires reaching a clear understanding of those factors, coordinating resources, and fostering and initiating change in individuals, families, and society.
- Roadmap to Violence Against Women Research: The NIJ Compendium
- New Approaches to Policing High-Risk Intimate Partner Victims and Offenders (NIJ Journal Issue 282)
- Employing Research To Understand Violence Against Women (NIJ Journal Issue 281)
- Child Trauma Response Team (CTRT): Pilot Program
- Intimate Partner Violence topic page
Dual system youth are a subset of “crossover youth” — juveniles who have been victims of maltreatment and have also engaged in delinquent acts. The dual system youth population consists of crossover youth who have entered, at some point, both the child welfare and juvenile justice systems. This vulnerable and high-risk group has unique, complex needs that demand a collaborative approach by the child welfare and juvenile justice systems.
The Dual System Youth Design Study, led by investigators at California State University Los Angeles and supported by NIJ and the Office of Juvenile Justice and Delinquency Prevention, suggests that more than half of the juvenile justice population has or will have child welfare involvement.
In forensic science, an alternate light source uses monochromatic light to detect and identify physical evidence, including bruises, body fluids, hair, clothing fibers, and other trace materials. This technology takes advantage of a material’s inherent luminescent properties that cause it to glow when struck with a specific wavelength of light.
Novel psychoactive substances (NPS), also referred to as designer drugs and synthetic drugs, are an emerging or re-emerging type of illicit substance. NPS are similar in structure and effect to common drugs of abuse, but differ enough that they evade detection with traditional tests and require new scheduling laws. NPS pose serious complications for both consumers and forensic scientists because their use may be linked to severe health problems and their chemical modifications makes them difficult to identify.
Read about research on NPS in the NIJ Journal article, Identifying New Illicit Drugs and Sounding the Alarm in Real Time, and in an article written by NIJ scientist Frances Scott, NPS Discovery and the Hunt for New Drugs of Abuse.
Mass spectrometry is a tool for measuring different fragments of a compound. In forensic science, mass spectrometry can be used, for example, to identify and discriminate individual drugs in seized substances. A mass spectrometer takes a sample, ionizes and breaks the compounds in it, and sorts the fragments by the ratio of their weight to their charge. The pattern of the captured fragments makes a spectral signature that can be used to identify the compound.
- Fast and Portable Drug Testing: Dual-Method Prototype Shows Promise for Court-Admissible Drug Testing
- Carbon-Based Fingerprint Powder as a One-Step Development and Matrix Application for High-Resolution Mass Spectrometry Imaging of Latent Fingerprints
- NIJ-funded research involving mass spectrometry
- Publications from NIJ-funded research involving mass spectrometry
NamUs is a national repository and resource center of information related to missing, unidentified, and unclaimed person cases. Funded and administered by the National Institute of Justice, NamUs fills the nation’s need for a central, online, secure database of unidentified remains and missing persons records. The database is searchable by all, with biometric and other secure case information accessible only to appropriate, vetted criminal justice users. All NamUs resources are provided at no cost to law enforcement, medical examiners, coroners, allied forensic professionals, and family members of the missing.
- Justice Department Fights for the Missing
- Justice Department Partnership Finds More than 300 Unidentified Persons Through Fingerprint Analysis
- Serial Killer Connections Through Cold Cases
- Searching for the Missing in a City of Millions
- Lost But Not Forgotten: Finding the Nation's Missing
Reintegration is when an individual transitions from being incarcerated in a prison or jail to living in a community and attempting to maintain a crime-free lifestyle.
Technology-facilitated abuse refers to harmful acts or courses of conduct facilitated through digital means that can compromise victims’ privacy and cause them to fear for their safety. Examples of such conduct are cyberstalking, nonconsensual pornography, swatting, doxing, and sextortion.
Personal harm from digital abuse extends far beyond the digital realm. These acts can cause serious psychological distress and damage relationships with family, friends, and partners and disrupt educational and professional pursuits.
Sextortion — A form of cyber extortion featuring an online attack on victim systems, for example through ransomware, in which offenders demand sexual images, sexual favors, or other things of value in exchange for stopping the attack.
Nonconsensual pornography — Distribution of nude or sexually explicit images or videos of an individual without consent.
Cyberstalking — Repeated use of electronic communications to stalk a person or group.
Doxing — Public release of private and sensitive personal identifying information about an individual without their consent. (The word “doxing” is derived from “documents.”)
Swatting — False report of an emergency to trigger an emergency response, specifically deployment of a SWAT team, to a location where no emergency exists.
Pediatric bruising patterns are tell-tale bruising patterns in injured children in order to differentiate between accidental injuries and physical abuse. Bruising on a child’s ear, buttocks, feet, or hands, for example, are not typical of accidental injuries and should alert physicians to possible abuse.
- Child Abuse or Accident? Bringing Science to Pediatric Emergency Departments and Forensic Investigations
- Impact Sites Representing Potential Bruising Locations Associated With Rearward Falls in Children
- Development of a Surrogate Bruising Detection System to Describe Bruising Patterns Associated with Common Childhood Falls
- Bruising as a Forensic Marker of Physical Elder Abuse
Using data, analysis, and research to complement experience and professional judgment, in order to provide the best possible police service to the public.
Evidence-Based Policing refers to scientific evidence, not evidence in the legal or investigative sense.
[note 1] Sampson, R.J. & J.H. Laub. (1993). Crime in the Making: Pathways and Turning Points Through Life. Boston: Harvard University Press.