Emergency and Dispatch Police Expert Witnesses: 5

Tony Turnbull is a retired Sergeant with the Sacramento County Sheriff's Office. He has over 30 years of Law Enforcement experience with over 20 of those years in Criminal Investigations.  Sgt. Turnbull spent over 20 years of his career in Investigations, including 6 years in Gangs and Narcotics and 16 years in the Homicide Bureau, including 3 years as the Homicide Bureau Supervisor and 5 years in Cold Case Investigations. 

Sgt. Turnbull is currently providing consulting and expert witness services, instructor with Robert Presley's Institute of Criminal Investigations, and working cold case homicide investigations as a retired annuitant at the Sacramento County Sheriff's Office.

Litigation Support - Sgt. Turnbull provides expert witness testimony and consulting services in both civil and criminal litigation, offering clear, methodical, objective opinions grounded in law enforcement standards, policy compliance, and constitutional policing. He also provides expert review of historical police investigations, applying current or past professional standards to cases. Domestic and international travel offered as needed.

Areas of Expertise:

Dr. Theron L. Bowman is a nationally recognized expert in Police Practices, Constitutional Policing, and Law Enforcement Oversight with more than 40 years of experience in public safety leadership, consulting, and litigation support. A former Chief of Police and Deputy City Manager for Arlington, Texas, he is the founder and CEO of The Bowman Group, a consulting firm specializing in police reform, accountability, and compliance monitoring.

Dr. Bowman has served as an expert in state and federal cases involving use of force, civil rights, internal investigations, and policy failures. His work spans major U.S. jurisdictions including New York City, Baltimore, Chicago, Memphis, Phoenix, Seattle, and Los Angeles County, and he has advised international policing initiatives in Bosnia, Kosovo, Haiti, Israel, Jordan, Iraq, and Afghanistan.

Litigation Support - Dr. Bowman has served as an expert in state and federal cases involving use of force, civil rights, internal investigations, and policy failures. His work spans major U.S. jurisdictions including New York City, Baltimore, Chicago, Memphis, Phoenix, Seattle, and Los Angeles County, and he has advised international policing initiatives in Bosnia, Kosovo, Haiti, Israel, Jordan, Iraq, and Afghanistan.

Attorneys and agencies retain Dr. Bowman for his deep operational insight, courtroom-tested credibility, and ability to translate complex police practices into clear, objective analysis.

Areas of Expertise:

Background Experience - Dr. Bowman holds a Ph.D. and MPA from the University of Texas at Arlington and is a graduate of the FBI National Executive Institute, FBI National Academy, and Senior Management Institute for Police.

A former CALEA Commissioner, Dr. Bowman has trained and advised agencies on constitutional policing, leadership, and accountability. His key areas of expertise include use of force, civil rights, police supervision, misconduct investigations, bias-free policing, and major event security.

He has held leadership roles with the International Association of Chiefs of Police and coordinated security for events such as the Super Bowl and World Series. His reform work includes guiding agencies under DOJ consent decrees and developing policies that strengthen accountability and community trust.

theron.bowman@tbowmangroup.com | (817) 502-9197

View The Bowman Group's Business Consulting Profile.

Dr. Roy G. Taylor is a current Chief of Police with over 40 years of experience in a wide-range of federal, state, local, and private criminal justice positions. Dr. Taylor specializes as an expert witness in Police Practices and Procedures and Law Enforcement and Criminal Justice. Current Positions:

• Chief of Police Blue Ridge Public Safety (2014)
• President/CEO Signal 88 Security of Charlotte (2012)
• President/CEO Capitol Special Patrol (2012)
• Chief of Police Capitol Special Police (2002)
• Lt. Colonel – Provost Marshal, Army National Guard (2000)
• Antiterrorism / Emergency Management Branch Chief DoD (2007)
• Provost Marshal Joint Civil Support Task Force, Joint Chiefs of Staff (2014)

Litigation Support - Dr. Taylor is called upon to analyze cases from both defense and plaintiff perspectives. His services include case review, written reports, deposition, and trial testimony as needed. 

Areas of Expertise:

View Roy Taylor's Consulting Profile.

Dr. Ron Martinelli, PhD, CMI-V, is a nationally renowned Forensic Criminologist and a federal/state courts qualified law enforcement and premises liability expert who is also a Certified Medical Investigator (physician's level) and a Certified Suicide Investigator. 

Dr. Martinelli directs the nation's only Forensic Death Investigations & Independent Review Team of 26 law enforcement, forensic and medical experts and specializes in officer-involved death cases, civilian self-defense shooting cases and premises liability/security cases. He is a forensic/law enforcement expert to the U.S. Department of Justice, several State Attorney Generals' Offices, numerous major municipalities and nationally prominent private law firms specializing in wrongful death, civil rights and premises liability. 

Dr. Martinelli is the prevailing expert in over 90% of his retained cases. He has saved defendants over $650M and earned plaintiffs over $290 million in jury verdicts and settlements since 2004. He is the media's go-to forensic expert for FOX News, One America News Network, CNN, HLN, Sky News, BBC, NPR, and the History & Discovery Channels. Dr. Martinelli is skilled in officer-involved shootings, in-custody deaths, crime scene reconstruction, forensics, applied sciences, human factors, psycho-medical emergencies and premises liability and security cases. His unique and extensive field experience, combined his academic and scientific credentials, excellent written reports and persuasive testimony, make him a very appealing expert to attorneys and juries alike.

Areas of Expertise:

• Arrests
• Search & Seizure
• Use of Force / Excessive Force - All Levels and Weaponry
• Officer Involved Shootings(OIS)
• In-Custody Deaths
• Criminal Investigations
• Law Enforcement & Corrections Practices, Training & Supervision
• Adult & Juvenile Corrections
• Law Enforcement Negligence
• Civilian Self-Defense, Premises Liability, Security, Foreseeable Harm
• Insurance Cases
• Human Factors

Chief Chet Epperson (Ret.), MBA, has over 44 years of experience as a Law Enforcement / Police Professional for the Rockford Police Department in Rockford, Illinois. Chief Epperson spent 33 years as an active law enforcement officer and 10 of those years as Chief of Police. 

Chief Epperson maintains practical experience as a municipal police chief, implementing several police reforms in his police agency along with accountability processes. He was instrumental in reforming the Rockford Police Department by enhancing its relationship with the community and providing internal and external transparency. Chief Epperson assisted in the formulation of a multi-jurisdictional task force to investigate officer-involved police shootings, in-custody police deaths, and serious uses of force.

Litigation Support - Since 2016, Chief Epperson has been serving as a Police Practices consultant, providing court-appointed expertise in police agency Federal District Court Consent Decrees. He is an expert in applying constitutional standards, state Law, policy, and practice to police incidents. Having Instructed courses on police use of force, internal affairs, and discipline, Chief Epperson is qualified to opine on cases of this nature for both plaintiffs and defendants. His police and jail litigation services include thorough reporting, deposition, and trial testimony as needed.

Areas of Expertise:

View AGR Police Practice Group's Consulting Profile.