Office of the Chief Medical Examiner

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Executive Staff of OCME

Dr. Roger Mitchell Jr.Chief Medical Examiner, Roger A. Mitchell, Jr. MD FASCP

Dr. Roger Mitchell Jr. is board certified in Anatomic and Forensic Pathology by the American Board of Pathology and a Fellow with the National Association of Medical Examiners (NAME).  Dr. Mitchell is the new Chair of the Strategic Planning Subcommittee for NAME and is the Immediate Past Chair for the Deaths in Custody Subcommittee.  Dr. Mitchell has recently served as the National Co-Chair for the National Medical Association’s (NMA) Working Group on Gun Violence and Police Use of Force.

He is a graduate of Howard University, Washington DC, and New Jersey Medical School, Newark, NJ.  Dr. Mitchell is licensed to practice medicine in Washington DC.  He has performed over 1400 autopsy examinations in his career and has testified as an expert on numerous cases.

He began the study of forensic science and violence prevention as a Forensic Biologist for the Federal Bureau of Investigation (FBI) – DNA Unit in January 1997. 

As the Chief Medical Examiner of a major city, Dr. Mitchell is uniquely positioned to understand the social determinants that lead to the violence affecting our most vulnerable communities.   He has a great interest in Violence as a public health issue and has recently co-authored position papers on The Violence Epidemic in the African American Community for the National Medical Association (NMA) and the Definition, Investigation, Postmortem Examination and Reporting of Deaths in Custody for the National Association of Medical Examiners (NAME). 

Dr. Mitchell recently served on the Forensic Science Standards Board (FSSB) for the National Institute of Science and Technology (NIST).  The Centers for Disease Control and Prevention (CDC), the U. S. Department of Justice (DOJ), and the National Institute of Justice (NIJ) frequently seek out his expertise on subjects such as violence, death investigation, and mass fatality management.  Dr. Mitchell has lectured for the Governments of cities located in India, Egypt, Bangladesh, Belize, and Liberia as well as for the International Coroners Conference in London, England.

Lastly, Dr. Roger A. Mitchell Jr. is a licensed minister serving as a mentor in his local community.  Dr. Mitchell often shares how drugs and violence have shaped his own life.  He is a husband to his wife of 17 years and a father to his three children.  Dr. Mitchell has pledged his professional career and personal time to the service of others.

Dr. Francisco J. Diaz

Deputy Chief Medical Examiner, Francisco J. Diaz, MD, FACP

Dr. Francisco J. Diaz received his medical degree in his native country, Dominican Republic.  After receiving his medical degree, Dr. Diaz trained in Anatomic Pathology at Conemaugh Memorial Medical Center in Johnstown, Pennsylvania/Temple University. In 2000, Dr. Diaz accepted a fellowship in forensic pathology with the Office of the Chief Medical Examiner in Philadelphia, Pennsylvania in affiliation with Hahnemann University (now Drexel University).

After completing the forensic pathology fellowship, Dr. Diaz joined the Office of the Chief Medical Examiner in Wayne County, Michigan as an Assistant Medical Examiner.  In January 2012, in affiliation with the Wayne County Medical Examiner’s Office, Dr. Diaz was appointed to the faculty of the University of Michigan, Department of Pathology as Assistant Professor. 

During his career, Dr. Diaz has performed more than 8500 autopsies and testified hundreds of times in circuit, district and federal courts.  He has also provided numerous civil depositions.  Dr. Diaz is the author of 35 peer-reviewed articles, abstracts, and presentations and has been invited on numerous occasions to speak at regional, national, and international conferences.

He is board certified in Anatomic Pathology as well as Forensic Pathology.  He is a fellow of the College of American Pathologists (CAP) and the National Association of Medical Examiners (NAME); where he serves on the membership, death in custody and government affairs committees. 

After joining DC OCME, Dr. Diaz was appointed to the faculty of George Washington University School of Medicine and Health Sciences and holds the rank of Assistant Professor.

Dr. Diaz enjoys reading and traveling when he is away from the office. 

Beverly Fields

Chief of Staff, Beverly Fields, Esq.

Ms. Beverly Ann Fields graduated from the Academy of the Holy Cross as Salutatorian of the Class of 1983.  Ms. Fields then attended Howard University and graduated in 1989 with a Bachelor of Science in Mechanical Engineering.  She then interned at the National Science Foundation in the Engineering Directorate, as assistant to the Director and Deputy Director. 

In the fall of 1989, Ms. Fields began working at Booz, Allen & Hamilton -- an engineering consulting firm as a Mechanical Engineer for the company’s Ship Systems Practice.  There she was responsible for consulting the Naval Sea Systems Command on the shock qualification and silencing of the TRIDENT submarine. 

In 1991, Ms. Fields entered Howard University’s School of Law where she was member of the Law Journal, Moot Court Team, and Phi Alpha Delta International Fraternity.  Graduating cum laude in 1994, she was hired as an associate of the law firm of Dewey Ballantine, where she practiced for two and one half years in the firm’s Energy Practice.  She is a member of the District of Columbia and Maryland State Bar Associations.

Beginning March 1997, Ms. Fields began a career on Capitol Hill over the span of 8 years worked her way up from a Legislative Assistant to Legislative Director and Chief of Staff.  She worked for three members of Congress serving on Oversight and Government Reform; Science, Space and Technology; Transportation and Infrastructure; and the Education and Workforce Committees.   

In 2004, Ms. Fields was hired as the Chief of Staff for the District of Columbia Office of the Chief Medical Examiner where she is charged with the administration of the agency, including budgeting, contracting and procurement, facilities and fleet management, legislative and legal matters, risk management, labor-management and human resources, and emergency response planning. She serves as the Public Information Officer

In addition to the above, Ms. Fields has been sought for numerous speaking engagements and cable television appearances regarding Congressional operations and public policy.   She has also produced and co-hosted a cable television show.  Throughout her career, Ms. Fields has received awards including being named one of thirty Fellows to participate in the John C. Stennis Congressional Fellowship for the 108th Congress.  She also successfully completed testing and is a member of the National Association of Parliamentarians.  Moreover, she has served as a Professor at the USDA Graduate School for the past eight years. 


General Counsel, Rodney Adams, Esq.

Becoming General Counsel at OCME has brought Rodney K. Adams’ career full circle.  After a semester of graduate forensic science study at George Washington University, Mr. Adams completed an LL M in Forensic Medicine at the University of Glasgow (Scotland), Faculty of Law as a Rotary International Scholar.  The University of Illinois, College of Law awarded a Juris Doctorate to him two years later.

After graduating from law school, Mr. Adams joined a large law firm that represented most of the Chicago area academic medical centers.  He was soon recognized for his expertise in advising and defending healthcare providers on matters involving patient care and other unique issues confronting the healthcare industry.  After six years, Mr. Adams relocated his practice to Richmond, Virginia and helped grow a law firm from fewer than thirty attorneys to more than three hundred attorneys in twenty-two offices around the country.  He tried more than seventy-five major cases to jury verdict, and was named Lawyer of the Year – Medical Malpractice, Defendant, by Best Lawyers in America.     

Mr. Adams was certified by the American Board of Trial Advocacy and appeared in Best Lawyers in America, Benchmark, Martindale Hubbell AV-Peer Rating and other rankings. He is a member of the Bars of the  District of Columbia and of Virginia and is retired from the Illinois State Bar.

Capping a more than thirty-year career in the private practice of health law, Mr. Adams accepted a two-year joint appointment at the University of Richmond Law School and at Virginia Commonwealth University, Dept. of Health Administration in 2018 to teach medical ethics, mental health law, corporate health law and health policy.  The graduate students in the MHA and MSHA programs flattered him with teaching awards.  At the College of William and Mary Law School, Mr. Adams has taught a medical malpractice trial practicum since 2015 that includes physicians and surgeons playing key roles in the trial held before a judge and jury.  He has also taught study abroad programs on global medical ethics for William & Mary undergraduates.  Teaching assignments have taken him to China, South Africa and Mauritius. 

A frequent speaker at national medical and law conferences, Mr. Adams has authored several books and book chapters. 


Chief Toxicologist, Samantha Tolliver Ph.D

Samantha S. Tolliver, Ph.D., is the Chief Toxicologist at the Washington, DC Office of the Chief Medical Examiner (DC OCME). She was previously employed as the Deputy Chief Toxicologist at the DC OCME and has been employed there since 2014.

Her fifteen years of toxicology experience include postmortem, driving under the influence, drug facilitated crime, pre/post exposure and work place drug testing. Her testimony experience encompasses both civil (family law) and criminal, within the States of Texas and Massachusetts, as well as the District of Columbia.

Dr. Tolliver holds a Bachelor’s Degree in Chemistry from West Virginia State University. She earned both her Master of Science in Forensic Science, as well as a Doctorate in Chemistry from Florida International University.

She is certified in toxicology from the National Registry of Certified Chemists. Dr. Tolliver has made scientific presentations at the Drug & Alcohol Testing Industry Association, the American Academy of Forensic Scientists and the Society of Forensic Toxicologists (SOFT). Dr. Tolliver is an active member of SOFT and the American Academy of Forensic Sciences.