SIGMA’s team members have over 250 years of collective experience and expertise in assessing and managing thousands of cases involving threats and other potentially dangerous behavior. SIGMA’s experts gained their threat assessment experience through careers in federal, state, and local law enforcement, education, criminal justice, mental health, and the law.  The work of SIGMA team members in threat assessment research and practice is referenced throughout several U.S. national standards and federal guides and has helped to define best practices in behavioral threat assessment and threat management.


SIGMA Leadership Team


Marisa R. Randazzo, Ph.D.
Chief Executive Officer and Founder

Expert Marisa RandazzoDr. Randazzo is CEO and founder of SIGMA, providing direct management and visionary leadership to all aspects of SIGMA’s work. She is an international expert on threat assessment and violence prevention, with over 25 years of experience investigating, assessing, and managing a broad array of threatening and dangerous situations.  Before creating SIGMA, Dr. Randazzo served for ten years with the U.S. Secret Service, most recently as Chief Research Psychologist, and has co-authored several leading books on threat assessment.  She frequently provides commentary to major news outlets on all aspects of violent behavior and prevention.  FULL BIO.


Cynthia L. Marble
Chief Operating Officer and Senior Vice President for Training Operations

Expert Cynthia MarbleCynthia Marble serves as SIGMA’s Chief Operating Officer and Senior Vice President for Training Operations, overseeing all training, consultation, and program development operations throughout the U.S. She is a nationally-recognized leader with over 25 years of experience in the fields of threat assessment and threat management, protective intelligence investigations, national security, executive protection, and global security operations. Before joining SIGMA, Mrs. Marble served for over 26 years with the U.S. Secret Service, most recently as the Special Agent in Charge for the U.S. Secret Service Houston Field Office. FULL BIO.


Dorian Van Horn
Senior Vice President for Investigative Operations

Expert Dorian Van HornDorian Van Horn is Senior Vice President for Investigative Operations, managing all of SIGMA’s case consultation engagements. She is a national leader in threat assessment and in family and sexual violence investigations. Before joining SIGMA, Ms. Van Horn served over 25 years as a Special Agent with the Naval Criminal Investigative Service (NCIS), including as Division Chief for the Threat Management Unit and the Insider Threat Program. She was appointed by the Secretary of Defense to the Defense Science Board Task Force on Predicting Violent Behavior. She was elected Secretary of the Association of Threat Assessment Professionals. FULL BIO.


Tara Conway, MA
Director of Operations

Expert Tara ConwayTara Conway is Director of Operations, managing SIGMA’s strategic reviews and assisting in the management of training operations and investigative operations. She has over 20 years of experience in threat assessment and protective intelligence, including 10 years with the U.S. Secret Service where she served as a senior analyst in the Intelligence Division and National Threat Assessment Center. Ms. Conway has extensive experience collaborating with U.S. and international intelligence agencies, Department of Defense elements, and with federal, state, and local law enforcement agencies. FULL BIO.


Jeffrey W. Pollard, Ph.D., ABPP
Vice President and Senior Psychologist

Expert Jeffery PollardDr. Jeff Pollard is Vice President and Senior Psychologist, providing management and clinical psychology expertise to SIGMA’s case consultations and training. Dr. Pollard is a Board Certified Licensed Psychologist, and founding member of George Mason University’s Threat Assessment Team, where he is Adjunct Faculty in the Department of Criminology, Law and Society where he teaches threat assessment. He also serves as the Behavioral Science Advisor to Mason’s Police Department. He has over 30 years of experience consulting on threat assessment to universities, colleges, private individuals, and government agencies throughout the country. FULL BIO


Denise Wolf, MA
Vice President and Organizational Dynamics Specialist

Expert Denise WolfDenise Wolf is Vice President and Organizational Dynamics Specialist with SIGMA. She has over 20 years of experience evaluating and enhancing the dynamics of workplaces and other entities, and in providing direct mental health services. Her experience includes leadership positions with major corporations and high-profile families, where she has managed physical security operations, facilities, and Human Resources. She helps teams and organizations to identify their vision, develop clear goals, and establish systems that facilitate communication and collaboration. She is trained in mediation, detecting deception, and corporate investigations. FULL BIO.


SIGMA Staff Members

Lea Bauer, M.Ed., CFE
Senior Threat Manager

Expert Tara ConwayLea Bauer is a Senior Threat Manager with SIGMA Threat Management Associates. She retired from the U.S. Secret Service as a Senior Special Agent, with 20 years of experience in threat assessment, protective operations, and physical security. Ms. Bauer has worked directly with the Department of Defense to develop and conduct training on threats from Islamic extremists; recruitment and radicalization; terrorist financing; and, interviewing techniques for Guantanamo Bay detainees. She is a certified fraud examiner, licensed private investigator, and formerly was a licensed psychotherapist. FULL BIO.


William Modzeleski
Senior Threat Manager

Expert William ModzeleskiWilliam “Bill” Modzeleski is a Senior Threat Manager specializing in K-12 threat assessment training and program development. He is a national leader in school safety and emergency management and former Associate Assistant Deputy Secretary of the U.S. Department of Education’s Office of Safe and Drug Free Schools. During his tenure at the Department of Education, he was instrumental in the development and implementation of several leading programs in emergency management and violence prevention.  He is co-author on the Safe School Initiative and on Targeted Attacks at Institutions of Higher EducationFULL BIO.


Dave Okada, CTM
Senior Threat Manager

Expert Dave OkadaLt. Dave Okada is a Senior Threat Manager and national expert in threat assessment and management. He has over 20 years of experience in threat assessment, 33 years in law enforcement, and has worked thousands of threat cases. He trains and consults on community-based threat assessment, as well as threat assessment K-12 schools, higher education, corporate settings, and the public sector. He is co-author of Assessing Student Threats-Implementing the Salem-Keizer System and other investigative guides for adult and student threat assessment teams. He serves as First Vice President on the ATAP National Board of Directors. FULL BIO.


Melissa Reeves, Ph.D., NCSP, LPC
Senior Threat Manager

Expert Dr. Melissa ReevesDr. Melissa Reeves, Ph.D., NCSP, LPC is a Senior Threat Manager and recently served as President of the National Association of School Psychologists. She is currently an Associate Professor at Winthrop University. Dr. Reeves is a nationally certified school psychologist, licensed special education teacher, licensed professional counselor, and former district coordinator of social/emotional/behavioral services. She has over 20 years of experience working in public schools and a private school, in addition to providing mental health services in day and residential treatment settings. Dr. Reeves is co-author of the NASP PREPaRE School Crisis Prevention and Intervention curriculum. FULL BIO.


Jeffrey J. Nolan, Esq.
Senior Legal Consultant

Expert Jeffrey NolanJeff Nolan is a Senior Legal Consultant in collaboration with SIGMA, a practicing attorney, and a Senior Counsel at Holland & Knight, LLP. Mr. Nolan advises and trains schools, colleges and universities regarding threat assessment practices, Title IX, the Clery Act, the Americans with Disabilities Act (ADA), Family Educational Rights and Privacy Act (FERPA) and other laws that apply in the higher education context, and he advises and trains employers on workplace violence prevention and employment law compliance. Mr. Nolan is featured in several lists of leading lawyers in labor and employment law. FULL BIO.


Peter Romary, GKMA; LLB, JD
Senior Legal Consultant

Expert Peter RomaryPeter Romary is a Senior Legal Consultant in collaboration with SIGMA; an attorney licensed to practice law in North Carolina, the District of Columbia, and before the U.S. Supreme Court; and, a Certified Arbitrator and Mediator. In his practice, Mr. Romary has concentrated on civil and criminal litigation, alternative dispute resolution, risk management, and on pro bono representation of over 100 victims of violence per year. Mr. Romary is the recipient of numerous honors, including a Knighthood and the Ellis Island Medal of Honor (the highest civilian honor sanctioned by Congress). FULL BIO.


Lynn Van Male, Ph.D., CTM
Senior Consultant

Expert Dr. Lynn Van MaleDr. Lynn Van Male is a Senior Consultant with SIGMA and an international expert on threat assessment and management in health care and human services settings. She is an Assistant Professor of Psychology at Oregon Health and Sciences University, a licensed Psychologist, and the national Director of the Workplace Violence Prevention Program for the largest integrated health care system in the United States. Dr. Van Male was also elected to serve as Second Vice President on the Association of Threat Assessment Professionals (ATAP) national Board of Directors. FULL BIO.


Richard M. Wilson, CPP
Senior Consultant

Expert Richard WilsonRich Wilson is a Senior Consultant with SIGMA and a national leader in the field of threat assessment.  Mr. Wilson is a former Assistant Chief of Police with the Arizona State University Police Department, with over 25 years of campus law enforcement experience and 20 years of experience in threat assessment case consultation and team training.  He also served as a crisis negotiation team leader.  Mr. Wilson is a Certified Protection Professional and has extensive experience in event security planning, to include numerous Super Bowl games, Olympics, NCAA Men’s Basketball Tournament, and Presidential and dignitary protection details.  FULL BIO.


William J. Zimmerman, CTM
Senior Consultant

Expert William ZimmermanWilliam Zimmerman is a Senior Consultant and one of the first Certified Threat Managers (CTM) in the world. Prior to joining SIGMA, Detective Zimmerman was a 32-year veteran of the U.S. Capitol Police, with duties in the USCP Threat Assessment Section since 1987 and retiring as the Senior Investigator. Detective Zimmerman was responsible for investigating threats against Members of the U.S. Congress, their families, and other statutory protectees. Mr. Zimmerman regularly reviewed, evaluated, and intervened with persons who threatened or engaged in inappropriate contact with Members of Congress throughout the United States. FULL BIO.


SIGMA Consultants