SIGMA’s experts have over 150 years of collective experience 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.


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

Expert Marisa RandazzoDr. Randazzo is CEO and founder of SIGMA and an international expert on threat assessment, targeted violence, and violence prevention.  She has over 25 years of experience investigating, assessing, and managing a broad array of dangerous situations, including assassination plots, school shooting threats, stalking situations, campus violence threats, workplace violence threats, and security breaches.  Before creating SIGMA, Dr. Randazzo served for ten years with the U.S. Secret Service, most recently as the agency’s Chief Research Psychologist.  She is co-author of several leading books in threat assessment and targeted violence.  Dr. Randazzo is often sought out for commentary by major television, radio, and print news outlets in the U.S. and internationally.  For Dr. Randazzo’s full bio, please click here.


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 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 where she managed the Secret Service offices in Houston and Austin, Texas, as well as Mexico City. She has over 25 years of experience conducting as well as supervising threat assessment and protective intelligence investigations on high-profile public officials and public figures. For Mrs. Marble’s full bio, please click here.


William Modzeleski
Senior Consultant

Expert William ModzeleskiWilliam “Bill” Modzeleski is a Senior Consultant with SIGMA Threat Management Associates and a nationally recognized leader in the area of school safety and emergency management. Mr. Modzeleski is a 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 Mr. Modzeleski was instrumental in the development and implementation of several programs related to emergency management and violence prevention, including the Safe Schools/Healthy Students Program; School Emergency Response to Violence; and the REMS program.  Mr. Modzeleski served as co-author with staff from U.S. Secret Service on the Safe School Initiative, and co-author with staff from Secret Service and FBI on study on Targeted Attacks at Institutions of Higher Education.  For Mr. Modzeleski’s full bio, please click here.


Jeffrey J. Nolan, Esq.
Senior 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.  He also served as a subject matter expert and faculty member for the national campus threat assessment training sponsored by the U.S.  Department of Justice, Office of Community Oriented Policing (COPS  Office).  Mr. Nolan has written and co-written several book chapters, scholarly articles and/or white papers on topics such as campus threat assessment, workplace violence prevention, the use of threat assessment methodologies in intimate partner violence and stalking cases, and trauma-informed investigation approaches.  For Mr. Nolan’s full bio, please click here.




Dave Okada, CTM
Senior Consultant

Expert Dave OkadaLt. Dave Okada is a Senior Consultant with SIGMA and is an expert in multi-disciplinary threat assessment and management. Serving in law enforcement for over 33 years, he has been a practitioner in threat assessment since 2000, chairs the Willamette Valley Adult Threat Advisory Team, and is a member of the Mid-Valley Student Threat Assessment Team, working on thousands of threat assessment cases throughout his career. He has trained and consulted in community-based threat assessment, K-12 threat assessment, higher education threat assessment, corporate threat assessment, and public-sector threat assessment. Lt Okada is a co-author of “Assessing Student Threats-Implementing the Salem-Keizer System” and has co-authored threat assessment investigative guides for adult and student threat assessment teams that are used throughout the nation. Lt Okada currently serves as First Vice-President on the ATAP National Board of Directors. For Lt Okada’s full bio, please click here.

Jeffrey W. Pollard, Ph.D., ABPP
Senior Consulting Psychologist

Expert Jeffery PollardDr. Jeff Pollard is the Senior Consulting Psychologist with SIGMA, 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 consulted to universities, colleges, private individuals, and government agencies throughout the country on threat assessment.  One of Dr. Pollard’s current projects is with the Virginia Tech Victims Family Outreach Foundation in establishing a national standard for campus safety. He serves as a member of the Advisory Council for the 32 National Campus Safety Initiative and on the Advisory Board for the Consortium for the Advancement of Threat Assessment and Management in Higher Education. For Dr. Pollard’s full bio, .please click here.



Melissa Reeves, Ph.D., NCSP, LPC
Senior Consultant

Expert Dr. Melissa ReevesDr. Melissa Reeves, Ph.D., NCSP, LPC is a Senior Consultant with SIGMA and recently served as President of the National Association of School Psychologists (2016-17). She is currently an Associate Professor at Winthrop University, SC in the psychology department and school psychology graduate program. 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’ 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 a co-author of the NASP PREPaRE School Crisis Prevention and Intervention curriculum, the first nationally and internationally disseminated school crisis prevention and intervention curriculum for K-12 schools. For Dr. Reeves’ full bio, please click here.


Peter Romary, GKMA; LLB, JD
Senior Consultant

Expert Peter RomaryPeter Romary is a Senior 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.  He now serves as Director of Student Legal Services and Adjunct Lecturer at East Carolina University.  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).  For Mr. Romary’s full bio, please click here.



Dorian Van Horn
Senior Consultant

Expert Dorian Van HornDorian Van Horn is a Senior Consultant with SIGMA Threat Management Associates and a nationally recognized leader in threat assessment and threat management.  Before joining the private sector, Ms. Van Horn served over 25 years as a Special Agent with the Naval Criminal Investigative Service (NCIS).  Ms Van Horn developed and was the NCIS Division Chief in charge of the Threat Management Unit and the Insider Threat Program.  She also oversaw the NCIS Family and Sexual Violence Program, and was responsible for the Death, Violent Crime, and the Cold Case Homicide Unit.  Ms. Van Horn was appointed by the Secretary of Defense as a Government Advisor to the Defense Science Board Task Force on Predicting Violent Behavior. For Ms. Van Dorn’s full bio, please click here.



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 subject matter expert on threat assessment and management in health care and human services settings. In addition to holding an appointment as an Assistant Professor of Psychology at Oregon Health and Sciences University, Dr. Van Male is a licensed Psychologist and the national Director of the Workplace Violence Prevention Program for the largest integrated health care system in the United States. She currently holds the elected office of Second Vice President on the Association of Threat Assessment Professionals (ATAP) national Board of Directors. Dr. Van Male is one of the first ATAP Certified Threat Managers (CTM), having beta-tested the CTM examination. She served on the Scientific Committee for the 4th, 5th and 6th International Conferences on Violence in the Health Sector; was an invited participant at the 2015 Federal Bureau of Investigation symposium on targeted violence prevention; and serves as a Contributing Editor of the Journal of Threat Assessment and Management. For Dr. Van Male’s full bio, please click here.



Richard M. Wilson, CPP
Senior Consultant

Expert Richard WilsonRich Wilson is a Senior Consultant with SIGMA and a nationally recognized leader in the profession of threat assessment.  Mr. Wilson is a former Assistant Chief of Police with the Arizona State University (ASU) Police Department, serving a community of over 72,000 students across four campuses.  During his 25 years of campus law enforcement experience, he distinguished himself as one of the earliest practitioners of behavioral threat assessment in higher education and has over 16 years experience in case management 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, summer and winter Olympics games, NCAA Men’s Basketball Tournament, and numerous Presidential and dignitary protection details.  For Mr. Wilson’s full bio, please click here.


Denise Wolf, MA
Organizational Dynamics Consultant

Expert Denise WolfDenise Wolf is an Organizational Dynamics Consultant with SIGMA.  She has worked with a variety of companies in a number of industries, ranging from high-tech to multi-unit retail and distribution.  Her experience includes leadership positions with Microsoft, AT&T Wireless, Starbucks, and Vulcan Inc., where she managed Systems and Physical Security, Facilities and Operations, European Properties, Yachts, and Human Resources.  She helps organizations identify their vision, develop clear goals to achieve defined objectives, and establish systems that foster open communication and the exchange of ideas.  She is trained in mediation, detecting deception, and corporate investigations.  For Ms. Wolf’s full bio, please click here.



William J. Zimmerman, CTM
Senior Consultant

Expert William ZimmermanWilliam Zimmerman is a Senior Consultant with SIGMA Threat Management Associates 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. He began his duties with the U.S. Captiol Police Threat Assessment Section in 1987 and retired as the Senior Investigator. While with the Threat Assessment Section, 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 in Washington, D.C. and throughout the United States. For Mr. Zimmerman’s full bio, please click here.



Tara Conway, MA
Threat Management Consultant

Expert Tara ConwayTara Conway is a Threat Management Consultant with SIGMA Threat Management Associates. She has extensive experience collaborating with national and international intelligence agencies, Department of Defense elements, as well as local, state and federal law enforcement agencies to analyze threats and coordinate efforts in the areas of response and prevention. She has a diverse background in threat assessment, having worked in the areas of protective intelligence, safety in schools, preventing targeted terrorist violence, and biometrics.  Prior to joining SIGMA, Tara worked with the U.S. Secret Service for ten years in threat assessment and protective intelligence, where she served as a senior analyst in the Intelligence Division and National Threat Assessment Center. She was responsible for the case management of subjects considered dangerous to U.S. Secret Service protectees.  For Ms. Conway’s full bio, please click here.