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How Prevalent is Violence in Missing and Unidentified Persons Cases?

For cases in which violence is a contributing factor, new research presents the importance of characterizing the NamUs database.
Date Published
February 28, 2022

The tally for missing and unidentified people in the U.S. routinely tops 600,000 people a year, and has rightfully been called the nation’s silent mass disaster.[1] While the majority of cases reported are resolved relatively quickly, the Department of Justice’s National Missing and Unidentified Persons System (NamUs) database is a valuable source of information for those involved in missing persons and unidentified persons cases. With over 21,000 active missing persons and almost 14,000 active unidentified persons case records, NamUs contains highly detailed descriptive case characteristics for many of these individuals.

People go missing for many reasons, and some of those reasons are violence-related. The extent to which violence is involved in missing and unidentified persons cases has not been examined directly, to date, due to a lack of empirical data on the subject. Recently, NIJ- and OVW-funded researchers had the rare opportunity to directly study the role that violence may have played in missing and unidentified persons cases through an examination of key characteristics in the NamUs database.

The empirical data used in this study also afforded an opportunity to study the role of violence in American Indian and Alaska Natives missing and unidentified persons cases, acknowledging that a 2016 study of these communities found that more than one out of three American Indian and Alaska Natives had experienced violence within the last year.[2] Using information in NamUs, researchers attempted to address the perception that there are a disproportionate number of American Indian and Alaska Natives missing and unidentified persons cases.

The current research sought to:

  • Understand the burden of violence in missing and unidentified persons cases in NamUs.
  • Discover how violence varies by gender of the victim.
  • Ascertain key case characteristics for missing and unidentified persons cases in violent and non-violent cases.
  • Examine the role of violence in American Indian and Alaska Natives cases.

Case Characterization

Researchers used text mining of NamUs case entries to classify cases as violent or nonviolent based on designated keywords, and then they examined additional case information to compare specific characteristics of violent versus non-violent cases. Key features, such as manner of death, DNA availability, age of case, and types of violence recorded (such as physical or psychological, among others) were analyzed in order to describe the cases and characterize the role of violence in missing and unidentified persons cases.[3]

Their research revealed that, in general, the level of violence estimated within the database was lower than expected, at about 10% of all missing persons cases. Researchers verified that most missing persons cases were resolved with the missing person found alive (as had been previously noted), and that this was true for both violent and non-violent cases.

Specifically, regarding violence and database characterization, the analysis discovered that:

  • Violence was more common in cases involving females versus males, for both missing and unidentified persons.
  • Physical violence was the most common form of violence, for both males and females.
  • Cases involving violence were more common in older age of case groups (“cold cases”) than younger ones.
  • For females, the highest proportion of missing persons cases (both violent and non-violent) was in juveniles under the age of 18, whereas cases for males were more evenly distributed across age groups.
  • Violence seemed to have no effect on case resolution for females, but it did for males, where cases were more often resolved if non-violent.
  • Due to data limitations with American Indian and Alaskan Natives cases, researchers were unable to discern any reliable frequency of missing and unidentified person cases among these population groups.

An Emphasis on Biometrics for Certain Cases

Based on the unique characteristics of violent cases that the authors discovered, recommendations were made to help improve the identification of violence and to enhance investigation and resolution of cases. Most unidentified persons’ remains (from violent and non-violent cases) were unrecognizable due to their condition, and researchers noted that the majority of cases were old (>20 years ago) for both males and females. Additional investigation, possibly through exhumation, could prove beneficial.

The team did notice some patterns in the data analysis that led them to emphasize that certain biometrics could be especially useful for UP case resolution. In particular, they encourage the increased use of DNA, fingerprints, and dental information. Fingerprints were especially helpful in identification of male MPs, as they were more likely to lead to successful identification in other databases.

Research Caveats

The overarching goal of NamUs has always been to bring together families, law enforcement, medical examiners, coroners, and forensic experts to expediently resolve missing and unidentified persons cases.

There are a few caveats to the work presented here:

  • The data in NamUs are dynamic and, as such, they are ever-changing. This study simply captures one moment in time within the database, for practical purposes.
  • The primary function of the NamUs database is to store, share, and compare information to locate missing persons and identify remains and, therefore, case entries may focus on biometrics and other identification data, while lacking data to indicate violence was a factor in the death or disappearance.   
  • Researchers involved with this work were uniquely qualified to study this database, as they were cleared for examining law enforcement-sensitive data.
  • The NamUs database is an operational criminal justice database that provides case management services for law enforcement agencies and medical examiner and coroner offices while allowing additional vetted data from the public. However, the use of the database is voluntary with few exceptions (i.e., some state mandates).

Caveats aside, this work provides seminal insight into missing and unidentified persons cases by capturing case violence along with context and detail in a way that has not been published to date. Characterization of the role of violence in these cases provides a better understanding of how violence may be related to other supplemental case characteristics, and helps researchers create a clearer picture of the extent to which violence is associated with these types of cases in general.

About This Article

The work described in this article was supported by NIJ award number 2016-MU-BX-K007, awarded to the University of North Texas Health Science Center.

This article is based on the grantee report “Cases Associated with Violence in the National Missing and Unidentified Persons System (NamUs)” (pdf, 94 pages), by Steven Hafner, B.J. Spamer, and Bruce Budowle, the University of North Texas (UNT) Health Science Center’s UNT Center for Human Identification.

Date Published: February 28, 2022