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MOSAIC Threat Assessment Systems (MOSAIC) is a method developed by Gavin de Becker & Associates in the early 1980s to assess and screen threats and inappropriate communications.

Walt Risler of Indiana University assisted in the development of the method. Robert Martin, the founding commander of the Los Angeles Police Department Threat Management Unit, now a Managing Principal with Gavin de Becker & Associates, heads up the MOSAIC Threat Assessment Unit.

Early MOSAIC systems were developed more than twenty-five years ago. Today, the enhanced, computer-assisted MOSAIC method is used by the U.S. Supreme Court Police to assess threats to the Justices, by the U.S. Marshals Service for screening threats to judicial officials, by the U.S. Capitol Police for threats against Members of Congress, by police agencies protecting the governors of eleven states, by many large corporations, and by more than twenty top universities.

Gavin de Becker received an award presented by the Director of the FBI and the US Attorney General for “for his outstanding work in developing a threat assessment module that has been of great assistance to law enforcement and criminal justice agencies all over the world.”

There are unique MOSAIC systems for different situations, including:

  • Threats and fear in the workplace
  • Threats by students
  • Threats against judges and other judicial officials
  • Threats against public figures and public officials
  • Domestic abuse situations

Unlike a checklist, MOSAIC facilitates an in-depth exploration of a situation, bringing attention to factors and combinations of factors that might otherwise go unnoticed.

A development team of experts in psychology, law enforcement, victims’ advocacy, prosecution, mental health, and threat assessment determines what areas of inquiry will produce the highest quality assessments. MOSAIC poses those questions to users, accompanied by a range of possible answers. MOSAIC calculates the value of the answers selected by the assessor, and expresses the results on a scale of 1 to 10. MOSAIC automatically produces a full written report, describing the factors that were considered.

MOSAIC’s on-line resources include library of research, publications, and training videos that users access at the moment they are most relevant. With each question suggested by MOSAIC, the system provides a button for Premise of the Question – providing research citations about why that particular area of inquiry is part of the assessment process.

Types of MOSAIC

MOSAIC – Public Figures (MAPP)

MOSAIC for assessing unwanted pursuit of Public Figures (MAPP) is typically used by agencies protecting elected and appointed officials (Governors and other constitutional officials, Federal and State Legislators), as well as by National Security Agencies, and iconic public figures.

Lieutenant Tom Taylor, who was assigned to the protective details of four governors and was a four-time president of the National Governor’s Security Association, writes about MAPP:

When you have evaluated three of four hundred threat cases, it is very helpful to know which guys are your top twenty. This enables the security detail to better focus its already limited resources. Also, each case is reevaluated with each new contact, so the evaluator can see whether the threatener is getting better or worse.[1]

MOSAIC – Judicial Officials (MAJ)

In the mid-nineties, Ted Calhoun of the United States Marshals Service undertook a major research project to advance knowledge about threats and attacks on Federal judges. He studied and analyzed more than 3,000 cases, and organized many new concepts to enhance assessments of threats against Federal judges. Calhoun felt that these threats – often made by people whose lives were directly affected by the Court – were inherently different from threats to other public figures, with whom the threateners rarely had any real contact. Further study indicated he was right.

The Marshals Service selected the MOSAIC method for applying Calhoun’s new research, and Gavin de Becker & Associates was commissioned to co-develop a new system: MOSAIC for Assessment of Threats to Judges (MAJ).

In Ted Calhoun’s book, Hunters and Howlers: Threats & Violence Against Federal Judicial Officials, he describes the method that evolved into this MOSAIC:

By drawing as complete a mosaic of the threatener and each of his inappropriate communications as possible, de Becker’s system identifies those situations requiring a defensive reaction or a proactive response. The problem is thus managed to the best and least intrusive protection of the victim. The whole approach is informed by an intelligent, comprehensive process of thinking. De Becker’s assessments are the best because he asks the most comprehensive questions, and he consistently asks them of every communication. To do less risks more.[2]

A variation of this MAJ is now used by Sheriff’s Deputies, bailiffs, and others tasked to protect judges and other judicial officials.

MOSAIC – Domestic Violence (DV-MOSAIC)

DV - MOSAIC assesses situations involving domestic violence. As of April 2010, DV - MOSAIC is available at no-cost to the public at

The U.S. Department of Justice published a five-year study on several approaches for managing and predicting the risk of future harm or lethality, including DV - MOSAIC. The study determined that when compared to the other approaches, DV - MOSAIC “performed best in predicting subsequent stalking or threats.” The study also found that MOSAIC tested highest on “sensitivity” correctly classifying most of the women that were re-assaulted; had the strongest correlation between the victims’ perception of risk of re-assault and risk of serious harm; captured relevant information equally well with victims of various ethnicities; had scores that were significantly associated with abuse; and provided uniformity of assessment (called Inter-rater Reliability) such that ten different people of different abilities and styles will come up with the same preliminary rating.[3]

DV - MOSAIC is used by many police departments including the Carson Sheriff’s Department in Carson, California. Law enforcement officials provide a copy of MOSAIC to the Los Angeles district attorney’s office to document the seriousness of the incident.[4]

MOSAIC – Workplace Violence (MAT-W)

MOSAIC – Workplace Violence assesses the three most likely sources of violence in the workplace: angry employees, angry former employees, and stalkers who pursue their targets at the workplace.

The development of this MOSAIC was guided by an Advisory Board of experts and practitioners from industry, education, and law enforcement.

This MOSAIC is most often used by professionals in security departments, legal departments, and human resources offices of large organizations, government agencies, and universities.

MOSAIC – Threats By Students (MAST)

The development of MOSAIC for Threats by Students (MAST) included an exploration into the pre-incident indicators of explosive school violence. The process recognized established knowledge and research, and also advanced thinking in this area by drawing on more than two hundred experts and practitioners from the fields of education, counseling, psychology, parenting, threat assessment, law enforcement, the judiciary. Even students participated in the development of MAST.

Most often, MAST is used by school administrators, counselors, and security/law enforcement officers.

Yale University uses MOSAIC for assessing threats made to Yale professors about two to three times a week. Chief James Perrotti stated that MOSAIC allows police to prioritize cases and better allocate their resources.[5]

In 2007, the Missouri Campus Task Force submitted a report to the Governor of Missouri on campus security and violence prevention. One of the report’s recommendations was, “Each institution should thoroughly evaluate the viability and appropriateness of using assessment tools (e.g. MOSAIC) designed to identify individuals with the potential for violent behavior.” [6]

The Oprah Winfrey Show

In April 2010, Oprah Winfrey dedicated an hour-long show to applying the MOSAIC method to domestic violence situations. It was announced on the show that Gavin de Becker & Associates would provide anyone with a MOSAIC assessment regarding domestic violence situations at no-cost. Audience members could access MOSAIC through or via[7]


In an article on the method, psychologist Hill Walker of the Institute on Violence and Destructive Behavior told Wired, "There are some serious validity issues here, some reputation-ruining implications." [8] Responding to claims that the program amounts to profiling, de Becker replied that MOSAIC for Assessment of Student Threats (MAST) “is the opposite of profiling in that it is always applied to an actual known individual, and it always explores actual behavior and circumstance.” He stated further that MAST “does not explore age, appearance, race, ethnicity, socioeconomic level, or any other demographic feature; profiling almost always does."[9]

Professor Laurence Steinberg also questioned the need and use of the software for predicting violence:

In the late 1990's, the number of school-age children who died from homicide averaged around 2,500 a year. But fewer than half of 1 percent of them were killed in or around schools. Let's say, for argument's sake, that each of these incidents involved a student perpetrator. In a nation of 90,000 schools, trying to pick out the dozen or so students a year who might commit murder is like looking for a needle in a haystack the size of Kansas.[10]

De Becker responded that MOSAIC for Assessment of Student Threats (MAST) is never applied to the general population of students, and rather just to those students who self-identify by making a threat.[11]

In 2005, the U.S. Department of Justice undertook a five-year study that assessed the several approaches to managing and predicting risk of future harm or lethality in domestic violence cases, including MOSAIC. Researchers had full hands-on access to every aspect of DV-MOSAIC for rating 1,307 battery cases. Comparing interviews, follow-up interviews, and criminal justice data, the project found that DV-MOSAIC scores were significantly associated with the level of abuse.

DV-MOSAIC tested highest on what the researchers called “sensitivity,” correctly classifying most of the women that were indeed re-assaulted. The study determined that when compared to the other approaches, “DV-MOSAIC performed best in predicting subsequent stalking or threats.”

In 2000, officials from the CIA, Yale University Police Department, the U.S. Capitol Police, the Administrative Office of the United States Courts, the U.S. Marshals Service, the California Highway Patrol, and other experts gathered for a comprehensive review of the MOSAIC used for assessment of threats to public figures. An updated system emerged, now known as the MOSAIC for Assessment of Public-figure Pursuit (MAPP).

In 2000, the State of California convened a group of experts to study the domestic violence MOSAIC and suggest any changes. A special MOSAIC called CAL-MOSAIC was developed and California provided it at no cost to the State’s 600+ police departments.

In 1999, the California Commission on Peace Officers Standards and Training (POST) convened a group of fifteen nationally-known subject matter experts on domestic violence for a line-by-line review of the DV-MOSAIC. After several upgrades and enhancements, the new system was made available at no cost to every one of the State’s more than 600 law enforcement agencies.

In 1999, the two largest school districts (Los Angeles and Chicago) participated in a project to develop a MOSAIC specially designed for assessing threats made by students. Paul Vallas, Superintendent of Chicago Schools, said at press conference:

Our schools need to avoid overreacting to threats that aren't substantial, and this system can help them in this respect. We can't be afraid of new technology, we can't be afraid of new approaches. Violence is a fact of life across this country, and we need to equip our principals with the analytical tools to make accurate calls as to which services and intervention support to make available to their students.

The MOSAIC systems that emerged, MAST (MOSAIC for Assessment of Student Threats) and MAST-U, for universities, is used by about 25 university systems.

In 1998, MOSAIC was selected by the National Victim Center as one of the “Top Ten Most Promising Strategies and Practices in Using Technology to Benefit Victims.”


  1. Taylor, Tom. (2000). Dodging Bullets: A Strategic Guide to World-Class Protection. Institute of Police Technology and Management.
  2. Calhoun, Frederick S. (February 1998). Hunters and Howlers: Threats and Violence Against Federal Judicial Officials in the United States. United States Marshals Service.
  3. Roehl, Janice Ph.D.; O’Sullivan, Chris Ph.D.; Webster, Daniel ScD; and Campbell Jacquelyn, Ph.D. (May 2005). Intimate Partner Violence Risk Assessment Validation Study. U.S. Department of Justice.
  4. Johnson, Tracy. (October 21, 1996). Software Assess Likelihood of Violence in Home. Los Angeles Times.
  5. Sachsman, Susanne (September 8, 1997). Prof Stalkers Beware: MOSAIC is here. [Yale News].
  6. Missouri Campus Task Force. (August 21, 2007). Security Our Future: Making Colleges and Universities Safe Places to Learn and Grow. Missouri Department of Higher Education.
  7. The Oprah Winfrey Show (April 16, 2010). Gavin de Becker.
  8. Forrest, Brett (June 2000). UltraViolencePredictor 1.0. Wired
  9. de Becker, Gavin (September 2000). Rants & Raves. Wired
  10. Steinberg, Laurence (April 22, 2000). Software Can't Make School Safe. New York Times
  11. de Becker, Gavin (May 5, 2000). Threats in School. New York Times

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