When prevention and intervention efforts fail and mass violence occurs, law enforcement efforts turn toward securing the scene and ensuring public safety. Officers and other personnel also collect evidence, track down leads, and investigate suspects.
Mass violence events result in chaotic crime scenes with many injured or deceased victims, potential suspects, and bystanders. When investigating such violence, whether it was the result of an explosive device, an active shooter, or another type of attack, evidence-based information and the latest technology can help guide law enforcement’s response.
Based on lessons learned from previous acts of mass violence and mass fatality incidents, the National Institute of Justice (NIJ) has published a series of guides for first responders who are responsible for protecting crime scenes, preserving physical evidence, and collecting evidence for scientific testing. Among the many things responders need to consider when arriving at the scene are the following:
- Securing the scene to remove or mitigate any hazards (e.g., a secondary explosive device) and ensure the safety of all responders and other individuals in and around the crime scene.
- Ensuring scene integrity and minimizing contamination, as well as any disturbance of physical evidence
- Documenting, preserving, and collecting evidence, especially for any potentially transient evidence (e.g., evidence on the victims or evidence that may be compromised by weather)
- Establishing a central coordinating post
- Managing press coverage, rumors, or misinformation
Although these practices are commonly understood among experienced officers, it is important for a consistent and efficient response that all potential responders are aware of agency policies and procedures and each responder’s roles and responsibilities.
Using Technology to Investigate Mass Violence Crime Scenes
The amount and variety of evidence collected at a typical crime scene can be extensive, and this is often even truer for the complex crime scenes that result from mass violence events. These crime scenes are at a high risk for contamination as first responders secure the area and assist injured victims. The scenes might also cover vast areas inside and outside buildings, potentially in highly populated environments.
Technology being developed today can help support crime scene documentation and investigation in the near future. Through an NIJ-sponsored researcher, Teledyne Scientific & Imaging has developed and tested a day-and-night real-time forensic imaging camera that is capable of enhancing objects and other forensic evidence. The hyperspectral camera collects and analyzes different wavelengths of light, including ultraviolet and infrared fluorescence. Among other advantages, this means that the camera can detect evidence, such as chemical stains, latent fingerprints, and blood and other bodily fluids, in daylight conditions. Such technology can increase the efficiency of crime scene processing and, thus, reduce contamination of potential evidence.
This innovative technology is then used as a triage tool to significantly reduce the labor involved in detecting and prioritizing crime scene evidence that will later be sent to a forensic laboratory for analysis. This can help identify the most probative evidence for laboratory testing, which in turn can reduce the risk of an evidence backlog if a large amount of evidence is submitted to a laboratory at once with no clear prioritization. Further enhancements to this camera prototype have been made, and the camera is now being considered for mass market development.
In 2014, NIJ awarded the New Jersey Institute of Technology a grant to create a more rugged, user-friendly, and portable version of a similar hyperspectral camera that can transmit data on the evidence over telecommunications channels to decrease the time and cost of forensic analyses at a crime scene.
When responding to an explosion, determining the weight, composition, and epicenter of the explosion is a top concern of forensic investigations. NIJ has recently supported the University of North Carolina at Charlotte in developing a low-cost, 3D-scanning scene reconstruction and evaluation tool to examine the structural and nonstructural building components after an explosion. By examining these “silent witnesses” to the blast, the tool can estimate the charge size and location and be used by investigators with minimal specialized training. Such a tool could greatly support law enforcement investigators as they work to understand and recreate a blast scene.
To evaluate the use of such crime scene imaging technologies, NIJ’s Forensic Technology Center of Excellence examined the operational use and technical requirements of three currently available imaging technologies. The resulting report, A Technical Evaluation of Three Panoramic Crime Scene Imaging Technologies, provides a basic understanding of crime scene imaging instruments and their use, benefits, and limitations. As a growing number of crime scene units recognize the benefits of using this technology to assist with bloodstain pattern analysis, shooting incident reconstruction, and explosion data collection, this report serves as an impartial resource that compares the features and capabilities of currently available imaging devices.
Law enforcement agencies have also been testing the use of unmanned aircraft systems (UAS) to document motor vehicle accidents and crime scenes. In addition to costing less to operate and maintain than manned aircraft, UAS have the added ability to go on missions that are too dangerous for officers. For example, they can be used during explosive ordnance disposal operations, search and rescue missions, active shooter incidents, and disaster response and recovery. UAS can provide valuable information to law enforcement and first responders while protecting officers from harm.
In suitable weather conditions, UAS have been used as flying camera platforms to create an accurate 3D rendering of motor vehicle accidents. In 2013, NIJ supported an evaluation of small UAS to see if they could be more efficient at mapping a crash scene compared to current laser mapping or roller measurement. Preliminary results found that, in a controlled environment, UAS provided a 40 percent reduction in the time required to work a motor vehicle collision scene. In addition to saving time, UAS could reduce the risk of officers being hit by a passing vehicle while working a crash scene. The Federal Bureau of Investigation reports that from 2004 to 2013, 101 officers were struck and killed by a motor vehicle while outside of their vehicle; 68 of those officers were directing traffic or assisting a motorist.
While this technology still needs to be tested for use in a live, field environment where wind, power lines, or bridge cables could impact its effectiveness, it is clear that UAS show the potential to speed the mapping and documentation of complex crime scenes, whether motor vehicle collisions or the aftermath of a violent mass attack. In 2015, NIJ supported a Miami University project in developing a hyperspectral library and software that can be used to identify human materials, such as skin, blood, hair, bone, and clothing. This technology can also be used on air vehicles such as appropriately sized UAS and satellites to identify downed law enforcement officers, search for survivors after a disaster, or identify human remains.
As innovative tools are being developed and tested for field use, agencies will have to consider their particular needs, the costs and limitations of the technology, local laws or policies that may affect the use of the technology, and any privacy or other concerns the community may have before procuring it. There is great potential for the latest technological developments to aid law enforcement officers in responding to mass violence, but technology is just one of many considerations for effectively dealing with mass casualty events. Scientific developments in other areas, such as identifying victims, can also be useful to law enforcement agencies after an incident of mass violence.
Identifying Victims and Death Investigation
Nothing prepared the U.S. forensic science community for the task of identifying those who died during the terrorist attacks on September 11, 2001. Following those attacks, NIJ brought together a group of experts to advise New York City’s Office of Chief Medical Examiner. Their experiences and recommendations were captured in the report Lessons Learned From 9/11: DNA Identification in Mass Fatality Incidents.
Today, this report still provides law enforcement and crime laboratories with valuable information to help them prepare a comprehensive plan for identifying victims of a mass fatality incident using forensic DNA analysis, including
- assessing the magnitude of victim identification needs and identifying the resources needed to respond
- gathering reference samples from personal items and DNA samples from victims’ families to aid in identification
- establishing lines of communication among law enforcement agencies, crime laboratories, victims’ families, and the press
- providing assistance to employees and volunteers working with the recovery effort
NIJ’s work on death investigation in mass fatality incidents can help law enforcement personnel better understand the death investigation process, how it supports the overall investigation, and how their role in recovery efforts can aid death investigations. In addition to transitioning the scene from rescue and recovery to crime scene and victim identification, law enforcement may have a role in reuniting families.
Mass casualty, large-scale, or multistate incidents—often called critical incidents—present unique challenges when it comes to finding missing individuals and reuniting families. The National Missing and Unidentified Persons System (NamUs) is a U.S.-wide centralized repository and resource center for locating and identifying missing persons and unidentified human remains and repatriating unclaimed persons. NamUs is a free online system that is used by medical examiners, coroners, law enforcement officials, allied forensic professionals, families of lost loved ones, and the general public who are trying to resolve cases. Since its development in 2007, NamUs has helped to resolve nearly 1,094 unidentified people and 1,662 missing-person cases.
NamUs was initially created to support individual cases of missing or unidentified persons, but has now taken up the call to help reunite families during critical incidents, including mass targeted violence events. NamUs is currently developing technology to provide the following resources:
- a centralized, secure data warehouse for victim accounting (missing, injured, deceased, and unaccounted-for victims)
- real-time victim data and situational awareness to help emergency officials guide the response
- an intuitive interface that ensures that the right data are collected about the missing individuals
- the ability for state emergency managers to collaborate with other states and federal resources seamlessly
- ways for the public to self-report themselves as safe
- training materials and environments for promoting preparedness
- free and secure access for state, local, and federal officials
NIJ and NamUs are advancing this work to identify human remains through a new collaboration with the FBI Laboratory. In March 2017, NamUs began to submit unidentified persons’ fingerprints to the FBI Laboratory’s Latent Print Support Unit in an attempt to solve open, unsolved cases. High-quality forensic examinations pertaining to friction ridge analysis are especially critical in missing persons’ cases, the existence of fingerprints on file is more common than the presence of DNA records. Since then, more than 1,100 fingerprint cards have been examined, resulting in more than 150 identifications, many of which were related to long-unsolved homicide investigations, including the identification of a young woman who had been killed crossing a highway 27 years ago. Identifying victims allows investigators to close cases and gives families answers.
Understanding the processes that crime scene investigators, medical examiners, and crime laboratories employ to investigate mass targeted violence will help law enforcement better collaborate with these agencies to support criminal investigations and identify victims to reunite them with their families. Such understanding will also allow law enforcement personnel to better target their crime scene and evidence collection procedures to ensure that their work effectively supports forensic analysis and death investigation during critical incidents.
Targeted and mass casualty violence is tragic and complex, and these critical incidents put a severe strain on the communities they affect, as well as the agencies responsible for protection and justice. Although the circumstances of each attack are unique, law enforcement can learn from the experiences of their peers in past attacks and use the innovative forensic science research and technological tools being developed to help investigate mass targeted violence in the future.
[note 1]National Institute of Justice (NIJ), “Crime Scene Investigation: Guides for Law Enforcement,” July 21, 2009; National Institute of Justice, A Guide for Explosion and Bombing Scene Investigation, June 2000.
[note 2] Milind Mahajan et al., Day and Night Real Time Signature Enhanced Crime Scene Survey Camera, January 2013.
[note 6] Forensic Technology Center of Excellence, A Technical Evaluation of Three Panoramic Crime Scene Imaging Technologies (Washington, DC: NIJ, 2013).
[note 7] U.S. Department of Justice, Office of Inspector General, Interim Report on the Department of Justice’s Use and Support of Unmanned Aircraft Systems, 2013.
[note 9] U.S. Department of Justice, Federal Bureau of Investigation, “Law Enforcement Officers Killed or Assaulted,” Table 61: Law Enforcement Officers Accidentally Killed, Circumstances at Scene of Incident, 2004–2013.
[note 11] NIJ, President’s DNA Initiative, Lessons Learned from 9/11: DNA Identification in Mass Fatality Incidents, September 2006; NIJ, “Identifying Remains: Lessons Learned from 9/11,” NIJ Journal 256 (January 2007).
[note 13] NamUs, internal report to NIJ, 2017.
[note 14] Ibid.; Keith Griffith, “Jane Doe Case Feature on Unsolved Mysteries is Finally Cracked After 27 Years Thanks to Cutting Edge FBI Fingerprint Analysis,” Daily Mail, May 12, 2017.