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Expert Panel Issues New Best Practices Guide for Cold Case Investigations

Date Published
September 25, 2019

Cold case statistics paint a bleak picture with an even bleaker outlook, if trends persist. An estimated 242,000 unresolved homicides occurred in the United States from 1980 to 2016.[1] Overall, roughly 40 percent of the homicides in the United States are unsolved. The clearance rate for homicides plunged from 78.3 percent in 1975 to 59.4 percent in 2016, and, from all indications, the decline will continue. Counting all crimes of violence, the numbers are even more daunting: less than half of violent crimes are cleared by law enforcement each year.

See NIJ’s Support for Science and Technology Advancement.

But there is hope. Even as the volume of unsolved crimes continues to soar, formidable new forensic technologies that can help crack cold cases keep emerging. Thus, there is great need, as well as great opportunity, for a commitment to refocusing attention on unsolved homicides and other violent crimes.

Now is the time to address the cold case crisis. Cases once considered unsolvable can be resolved today.

This quote comes from the National Best Practices for Implementing and Sustaining a Cold Case Investigation, a product of the National Institute of Justice (NIJ) Cold Case Investigation Working Group (Working Group) and NIJ. Their mission: to create a best-practice guide to support law enforcement agencies in developing a long-term strategy to address cold cases in their jurisdictions.

The Working Group’s 23 recommendations for best practices are designed primarily to assist law enforcement administrators and command staff. The recommendations fall into five categories:

  1. Determining the needs and scope of a cold case unit
  2. Designing a cold case unit
  3. Implementing a cold case unit
  4. Operating a cold case unit
  5. Identifying support for a cold case unit (including law enforcement and academic partnerships)

Generally, the best practices report speaks to a need for operationally separate, professionally managed cold case units within law enforcement agencies, with experienced investigators assigned exclusively to the unit, with ready access to DNA databases and other innovative forensic tools, and with regular, systematic assessments of the jurisdiction’s cold case inventory. (See the Working Group’s 23 Best Practice Recommendations, below.) The Working Group emphasized the need for agencies to empower cold case investigators to focus their energies and resources on these long-unsolved crimes.

The three dozen Working Group members were selected for their elite expertise in the study or investigation of cold cases and the interests of victims of crime. The group members come from law enforcement agencies, prosecutor offices, missing persons programs, academia, and state and federal agencies. The Working Group’s recommendations represent a consensus reached through extensive research and deliberations. The group stressed that their recommendations are advisory, not mandated by any government entity.

Although the term “cold case” has gained broad public exposure and acceptance, the Working Group urged awareness that the term may be offensive to crime victims and their families, who may infer that authorities have given up on cases classified as “cold.” The report noted previous guidance to that effect from the National Sheriffs’ Association.

See The Working Group’s Definition of “Cold Case”—Unsolved for at Least Three Years

The Dearth of Cold Case Units in Law Enforcement Agencies

Currently, only a fraction of U.S. law enforcement agencies have dedicated cold case units, and only one out of five departments has formal protocols for initiating cold case investigations. (See Figure 1.)

Figure 1. Percentage of Cold Case Units in U.S. Law Enforcement Agencies
Dedicated cold case units, all surveyed departments 7%
Dedicated units, departments with 100+ officers 18%
Dedicated units, departments with 50 or less officers 1%
Investigators who work on call cases (no dedicated unit), all surveyed departments 10%
Formal protocols for initiative cold case investigations, all surveyed departments 20%

Source: Robert C. Davis, Carl Jensen, and Karen E. Kitchens, Cold Case Investigations: An Analysis of Current Practices and Factors Associated with Successful Outcomes (RAND Center on Quality Policing, 2011).

High-Level Justifications for Cold Case Units

The Working Group’s report and its recommendations leave no doubt about the urgency of the United States’ cold case problem, nor about the moral and public safety imperatives informing the need for renewed action on those cases. The report identified five primary justifications for cold case units: (1) criminal justice, (2) public safety, (3) public trust, (4) clearance rates, and (5) cost savings.

Criminal Justice

With respect to criminal justice considerations, the report focused on crime victims’ rights, noting that victims’ issues and concerns are “an integral part of policing in the 21st century.” When a case goes unsolved, the victim is doubly victimized by the absence of justice. The report noted that faith in the criminal justice system depends on the public’s belief that laws will be enforced. Living victims need to be assured that they are not forgotten and that the persons who committed the crime will be held accountable.

Public Safety

One aspect of the public safety justification for cold case units is the prominent presence of those who commit repeated offenses in cold cases. The report noted that 71 percent of those who commit violent criminal offenses are rearrested within five years of release from prison. Researchers have also found that serial rapists are more prevalent than previously thought, the report said, citing findings of a 2018 report by the Begun Center for Violence Prevention Research and Education and the Cuyahoga County (Ohio) Sexual Assault Kit Task Force. Thus, solving cold cases can prevent future victimization by taking persons who repeatedly commit offenses off the street.

Public Trust

With respect to preserving public trust in law enforcement, the Working Group noted that when criminal investigations are not resolved, police performance falls short of public expectations:

Resolving cold cases is an important contributor to preventing crime, increasing public safety, and increasing the favorable image of law enforcement — that is, fulfilling law enforcement’s mission and maintaining public trust.

Clearance Rates

Law enforcement has long looked to clearance rates—an agency’s rate of solving crimes and moving them off the books—as a key indicator of effectiveness. But additional factors need to be considered in gauging the effectiveness of a cold case unit, where it is a given that some cases will likely never be solved. (See “Clearance Rates Are Not the Whole Story” section below.) Nonetheless, the creation or expansion of dedicated cold case units could improve clearance rates for many agencies.

Cost Savings

Realizing cost savings and making the case for a unit in economic terms can be challenging because many of the anticipated benefits of a cold case unit are subjective or noneconomic in nature. How does one quantify the value to parents of solving the long-ago killing of their child, in terms of avoidance of further suffering and uncertainty?

Other benefits of cold case efforts are more amenable to measurement. For example, the report noted large and increasingly effective DNA databases may reduce the need for and cost of law enforcement investigative resources by making solving cold cases more efficient or less time-consuming.

Reasons to Reopen Cases

The Working Group called upon law enforcement to take advantage of new forensic technologies and crime databases.

The report identified the following primary reasons to reopen cold cases:

  1. Advancements in forensic technology. Evidence once deemed unsuitable for testing may now yield probative evidence or leads.b. Databases have significantly improved with ease of uploading forensic data, better search algorithms, and interoperability across systems,
  2. Changes in relationships over time
  3. New leads through fresh case and evidence review
  4. Increased public support and interest in cold case investigations
  5. Improvements in information management

The Crime-Solving Power of Databases and DNA

The strengthening and proliferation of forensic databases add real power to investigations and can turn cold cases into hot cases in an instant. In addressing how to operate a cold case unit, the report underscored the need for investigators to move quickly on a database hit:

Database hits often occur long after an investigation is initiated. Without a proper protocol to address hit notifications, agencies face confusion about what is needed and who should respond. Leaving a notification unaddressed equates to ignoring a suspect who is likely the perpetrator.

The Working Group report noted that linking cases through databases “multiplies the investigative information available for each of the linked cases.”

Overall, the volume of records in forensic databases, such as those for DNA, is increasing exponentially each year. The process of populating DNA databases, the report said, generates cost savings for law enforcement agencies by providing valuable leads.

Advances in DNA technology, including the ability to detect and analyze trace amounts of DNA, have greatly increased the opportunity to successfully analyze DNA from degraded biological evidence. As of December 2018, the National DNA Index System contained almost 13.6 million profiles from convicted offenders and more than 3 million arrestee profiles, according to data from the FBI, its Combined DNA Index System (CODIS), and the National DNA Index System (NDIS).

NIJ and the Bureau of Justice Assistance—sister agencies within the U.S. Department of Justice’s Office of Justice Programs—have worked together to resolve the backlog of unanalyzed sexual assault kits across the United States. Largely as a result of those efforts, by December 2017, more than 1 million kits had been analyzed for DNA and more than 400,000 forensic crime scene DNA profiles were uploaded to CODIS.

Advancements That Can Help Solve Cold Cases

Key forensic technology advancements that can help solve cold cases were identified in the report.

  • The National Missing and Unidentified Persons System (NamUs), a suite of services and databases for missing persons and unidentified human remains
  • New and novel methodologies in forensic DNA testing
  • Advanced fingerprint identification technology and the FBI’s Next Generation Identification system
  • The National Integrated Ballistic Information Network (NIBIN), run by the Bureau of Alcohol, Tobacco, and Firearms; a growing imaging database system for cartridge casing evidence
  • Scientific advances yielding additional relevant information from bone, tissue, and biological samples upon reexamination
  • Innovative techniques used for crime scene analysis
  • Additional forensic sciences, such as trace fiber analysis, analysis of hair to determine where a person has traveled, and personal characteristics such as sex and race

Clearance Rates Are Not the Whole Story

Citing work by the Police Executive Research Forum (PERF), the Working Group observed that, as investigators are unable to resolve crimes, their caseloads increase, creating a drain on agency resources and, in turn, increasing cold case volume. PERF describes this pattern as a vicious cycle.

The Working Group observed that declining clearance rates are a major indicator of the cold case crisis. At the same time, clearance rates alone are not a full measure of agency efforts—especially with respect to cold case investigations, which are “vastly different from initial investigations,” according to the Working Group. The report acknowledged there is no one instrument for measuring the success of cold case investigations, but added, “Nonetheless, as offenders are removed from the public through the resolution of unsolved cases, we can project that crime rates will decrease while arrests and clearances will increase.”

Decision Makers Facing Budget Pressure Should Focus on Benefits of Cold Case Resource Commitments

The Working Group concedes that cold case units are often vulnerable when agencies decide to invest in an increased police presence in communities. But the Working Group submits that “it is critical that decision makers understand the benefits of providing resources for unresolved crimes.”

The report concludes,

The time has come for forward-thinking, innovative law enforcement leaders to embrace the investigation of cold cases as an integral part of their agencies’ core mission. At the very least, bringing a cold case up to today’s technological and investigative standards gives the case a better chance of being resolved.

Recommendations of the Cold Case Working Group

Determining the Needs and Scope of a Cold Case Investigation Unit

  1. Define the specific parameters of a cold case with consideration for applicable laws and agency policies and practices.
  2. Conduct an initial needs assessment to determine the resources needed to create and sustain a successful cold case unit.
       2a. Conduct an inventory of the number of unresolved cases.
       2b. Identify and record all unresolved cases in a computerized information management system during the initial inventory.
       2c. Conduct periodic needs assessments to ensure that investigative activities conform to current investigative practices and that the operational needs remain in alignment with the agency’s operations and mission.

Designing a Cold Case Unit

  1. Appoint a project lead to oversee the implementation of the cold case unit. Choose an individual who understands the agency, the process of unresolved case investigations, and the jurisdiction’s administration.
  2. Collect performance metrics relevant to cold case activities in addition to clearance rates. Use appropriate data analytics to examine the performance and needs of the unit.
  3. Agencies should not assign cold case investigators to incoming cases, temporary assignments, or non-cold case projects.
  4. Limit investigators to actively investigating no more than five cold cases at any one time.
  5. Assemble stakeholders and representatives of affected agencies to provide input and assistance in planning the cold case unit, including how it will be structured, implemented, and operated.
       7a. Identify agencies of similar size and structure that have established cold case units as informational resources.
       7b. Formalize and document partnerships among stakeholders with a memorandum of understanding.
       7c. Bring together multidisciplinary subject matter experts to provide diverse knowledge, resources, and perspectives in all facets of cold case review and investigation.

Implementing a Cold Case Unit

  1. Implement a cold case unit as a separate, defined unit within an agency. Position the unit in an existing bureau, division, or branch responsible for investigative activities.
  2. Identify a lead agency for the unit if multiple agencies or multiple jurisdictions are engaged.
  3. Create written protocols and directives to detail cold case organization, operations, and investigations.
       10a. Specify the job duties for cold case investigators, supervisors, and other personnel in the unit’s policies and procedures.
       10b. In a multiagency/multijurisdictional cold case unit, implement protocols detailing the distinct roles of each participating agency.
       10c. Include protocols for continuity of operations and staff transitions.
  4. Incorporate a trauma-informed approach into cold case unit operations.
  5. Employ a victim-centered approach in the daily operations of cold case investigations.
       12a. Create protocols addressing situations in which a victim does not support continued investigation of the case.
       12b. Include a detailed plan for communication with victims and victims’ families in the cold case unit protocols.
       12c. Incorporate a victim specialist and/or advocate into unit protocols and operations.
  6. Select experienced investigators for the cold case unit, preferably with a minimum of five years of investigative experience.
  7. Assign at least two full-time investigators to cold case investigations.
  8. Cold case investigators should use and consider nontraditional resources, such as volunteers and academia, in cold case investigations.
  9. Assign investigators to investigative duties only. Delegate all other operational activities of the unit to support staff. Assign administrative work to non-investigative personnel or others to increase the efficiency of the unit.

Operating a Cold Case Unit

  1. Organize cases by starting with the investigations that have the most apparent means of resolution. Consider database hits, ease of resolution, and community interest when selecting cases.
  2. Perform an initial comprehensive agency audit to locate, document, and package all evidence according to current standards. Perform evidence audits at least once a year, and update agency files to reflect the results of the audits. Document the location, condition, and laboratory analyses of evidence in a computerized information management/tracking system.18a. Review all evidence to determine its evidentiary value and evaluate whether new forensic methods could be used for further examination.18b. Review and update evidence retention policies as needed to prevent the destruction of evidence in unresolved cases.
  3. Review all case files to ensure that they are current with contemporary standards and that all investigative opportunities have been exhausted. Conduct subsequent reviews periodically to ensure that cases remain current with the available technology and investigative processes and to identify any new investigative opportunities.
  4. Actively engage a prosecutor with cold case operations.
  5. Maintain a public-facing list of all unresolved cases (e.g., a cold case website).
  6. Develop a media information dissemination strategy. Detail this strategy in the agency protocols. Designate an agency public information officer to act as media liaison.

    Identifying Support for a Cold Case Unit

  7. Utilize academic resources when possible and appropriate. These resources may include technologies, students, and faculty with subject matter expertise.

NIJ directs and funds the development and implementation of technology for use in open, previously unsolved cases and other areas of criminal justice. NIJ’s mission includes both the advancement and evaluation of existing scientific investigative tools and the development of new tools. NIJ also supports the Forensic Technology Center of Excellence (FTCoE) to help bridge the gap between criminal justice research and practice.  

NIJ made an early push to help law enforcement integrate forensic DNA into open, previously unsolved case procedures with its Solving Cold Cases with DNA grant program. From 2005 to 2014, the federal research agency awarded over $77 million to state and local agencies for open, previously unsolved case investigations. The program facilitated the review of more than 140,000 unresolved cases, 5,000 CODIS uploads, and 2,000 hits. From its decade of experience in supporting such investigations, NIJ initiated the best practices development program that gave rise to the Cold Case Investigation Working Group and its new best practices recommendations.  

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As a foundation for its analysis, the Working Group sought to bring clarity to the often–inconsistent definition of the term “cold case” across jurisdictions. The length of time a case must remain unresolved, with no viable leads, to qualify as a cold case can range from one year to as long as five years, depending on the jurisdiction. For purposes of its best-practice recommendations, the Working Group adopted this definition:

A case, such as a violent crime, missing person, or unidentified person that has remained unsolved for at least three years and has the potential to be solved through newly acquired information or advanced technologies to analyze evidence.  

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Date Published: September 25, 2019