Police Practices and Procedures Expert Witnesses: 20

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.

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:

Beth A. Mohr, CFE, FSA, CFCS, CAMS, CCCI, MPA, PI, is a Police Practices expert with over 30 years of sworn and non-sworn investigative experience.  Ms. Mohr has testified as an expert in numerous state and federal court proceedings, depositions, and administrative hearings in federal and state courts, including New Mexico, Ohio, Illinois, Arizona, California, and Washington State.  Ms. Mohr has testified on a variety of subjects, including police procedures, police misconduct, white-collar crime, and fraud examinations.  Her expertise has been verified by the courts via a Daubert challenge, in which Ms. Mohr was found to be qualified as an expert in police practices generally, and well as the specific areas of interviewing, interrogation, false and recanted confessions, cognitive bias, investigations and investigative failures, vice, and human trafficking.  Ms. Mohr is neutral, fair, and her opinions are rooted in provable facts, as well as academic literature, where appropriate.  She strives to balance her cases between defense and plaintiff-sided cases, and also provides habeas consulting services.  

Ms. Mohr is credentialed as a Nationally Certified Law Enforcement Instructor by the IADLEST, and is one of fewer than 150 individuals who have been nationally certified as an expert law enforcement instructor.  She is a Certified Fraud Examiner, Certified Force Science Analyst (FSA) Certified Anti-Money Laundering Specialist (CAMS), Certified Financial Crimes Specialist (CFCS) and a Certified Cyber Crimes Investigator (CCCI).  She is also a Private Investigator (PI) licensed in New Mexico, Arizona, Texas, and California.  

Areas of Expertise:

• Police Practices and allegation of Police Misconduct
• Excessive Force, Deadly Force & Use-of-Force
• Taser, ECWs, and other uses of force intended to be less-lethal
• Interviewing, Interrogations & False and Recanted Confessions
• Police Ethics & Ethical Failures
• Cognitive Bias, Confirmation Bias
• Investigative Failures
• False Arrest
• Failure to Train, Failure to Supervise, Monell Claims
• Evidence Handling
• Police Policy, SOPs
• Habeas Consulting, including death penalty cases
• Sex Trafficking and Human Trafficking
• Sexual Assault
• Fraud & White-Collar Cases
• Retaliation & Qui Tam
• Workplace Violence & Sexual Harassment
• Private Investigations & PI Failures

During her career with the San Diego Police Department, Ms. Mohr was awarded three Commanding Officer’s Citations, which were the highest awards offered by the San Diego Police Department for investigative acumen at the time.  After retiring from the San Diego Police Department, she conducted death penalty mitigation investigations and other complex felony investigations, including homicide and white-collar cases, for the Whatcom County, Washington, Public Defender’s Office.  This includes conducting investigations of allegations of police misconduct for the City of Albuquerque Independent Review Office. Ms. Mohr recently chaired the City of Albuquerque’s Police Oversight Board, a civilian board that was created as part of the US Department of Justice’s Consent Decree with the City of Albuquerque and the Albuquerque Police Department.

Ms. Mohr has published a chapter entitled “Skepticism”, in the newly-released book The Art of Investigation Revisited, as well as having penned articles for bar journals and other peer-reviewed publications.  Ms. Mohr has taught courses on law enforcement topics, including interviewing techniques, investigative ethics, evidence collection, financial and fraud investigations, and many other topics. Her ethics courses, investigative courses, and fraud courses are certified for law enforcement credit.

“We settled the case...for $5 million. Your report played a huge role in that.  Thank you for everything!”  Nick H. 

Aaron T. Olson specializes as an expert in police practices and human resources lawsuits. His knowledge and skills come from a career in law enforcement, former human resources investigator, being an expert witness, private investigator, adjunct professor, author and trainer. 

Background Experience: Mr. Olson has 26 years of police experience with the Oregon State Police with management assignments in communications, recruitment, and patrol. He supervised and evaluated both police and non-police employees. He was a member of the OSP Procedures and Rules Advisory Committee and worked with Oregon's Department of Justice legal team in rewriting and validating OSP's trooper and cadet applicant hiring process. 

As a patrol supervisor, Mr. Olson directed major crime scenes and motor vehicle fatalities investigations. He reviewed and approved administrative, police, and use of force reports. He investigated allegations of police officer misconduct, conducted background checks, and participated in specialized tasks in community policing, dignitary protection with the U.S. Secret Service and other law enforcement agencies. In his tenure he had personal experience in police pursuits, the use of physical force and deadly force and next-of-kin death notifications.  

Mr. Olson is a former human resources investigator with Local Government Personnel Institute, Salem, OR. He conducted background and misconduct investigations on city and county employees and city and county elected officials, as well as city police chiefs. The misconduct investigations included sexual harassment, discrimination, retaliation and hostile work environments. He wrote the investigative reports and made the findings of facts on all misconduct allegations.

Besides being an expert witness, Mr. Olson is a private investigator. He is insured and bonded and licensed through the Oregon Department of Public Safety Standards and Training, Private Investigator License #113509. Mr. Olson is a contract expert consultant to the Oregon Public Defense Commission on police practices and defendant use of force. His vendor number is 1833121097-000. 

Olson is a published co -writer of multiple books, CARE Approach: Seeking Solutions to Human Problems and Multicultural Law Enforcement: Strategies for Peacekeeping in a Diverse Society. Further, he is an adjunct professor teaching at a community college and state university.

Expert Witness: Mr. Olson has experience as an expert on cases involving police misconduct, police procedures, police use of force, police pursuits, wrongful death, personal injury, citizen use of force, murder, manslaughter, attempted murder, assault, felon in possession of a firearm, employer investigations on employees, employer negligent hiring, negligent training, negligent supervision, negligent retention, management performance and retaliation. He has experience in testifying in civil and criminal court cases, as well as civil depositions. Mr. Olson's services are available to attorneys' representing plaintiffs and defendants in state and federal court cases. Contact him today for a free initial consultation.

Areas of Expertise:

View Aaron T. Olson'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

Andreu Experts is a premier expert witness and consulting firm specializing in Law Enforcement Practices, with a distinct focus on Homicide Investigations, Use of Force, and Complex Criminal Case Analysis. Founded by a former Chief of Police with more than 45 years of distinguished law enforcement experience—including over two decades dedicated to homicide investigations—Andreu Experts delivers authoritative, fact-driven opinions grounded in real-world investigative leadership.

Their firm provides comprehensive expert services to both plaintiff and defense attorneys in state and federal courts. They are retained in cases involving wrongful death, police procedures, investigative failures, officer-involved shootings, and allegations of misconduct. Every opinion rendered is the product of meticulous case review, careful analysis of reports, witness statements, forensic evidence, and adherence to generally accepted law enforcement standards and practices.

What distinguishes Andreu Experts is not only the depth of experience, but the credibility and clarity brought to each case. Having led major investigations and supervised detectives in high-stakes environments, their principal understands how investigations should be conducted—and where they fall short. This perspective allows them to identify critical issues, explain complex procedures in plain terms, and assist attorneys in building compelling, well-supported arguments.

Services include case evaluation, report writing, deposition and trial testimony, and trial preparation support. They work closely with legal teams to strengthen case strategy, anticipate opposing arguments, and present findings in a manner that resonates with judges and juries alike. Whether retained early in litigation or brought in to assess an existing case, Andreu Experts provides objective, defensible opinions that stand up under scrutiny.

Andreu Experts' commitment is to professionalism, integrity, and precision. They do not advocate—they analyze. Their role is to assist the trier of fact in understanding what occurred, why it matters, and how it aligns with accepted law enforcement standards. When experience matters and credibility is critical, Andreu Experts is a trusted partner in the pursuit of justice.

Dr. John R. Black is a recognized expert with extensive experience in international, federal, and state courts on Lethal Force, Police Use of Force, Officer-Involved Shootings, and Civilian Self-Defense, blending forensic analysis with human-centered perspectives and systems thinking. Dr. Black employs a systems thinking approach that enables him to view incidents from multiple perspectives. He regularly speaks to Police leadership, investigators, lawyers, and organizations about how we think about the process of inquiry, our biases, and our sensemaking.

Litigation Support - Dr. Black is qualified as an expert witness in state and federal courts related to police practices, police use of force, decision-making, officer-involved shootings, police tactics, police training, incident command, and police / jail operations. He is also qualified with similar expertise for civilian self-defense and use of force events.

Expert in Use of Force & Lethal Force Incidents & Decision-Making

In cases involving force--lethal force, understanding decision-making is as critical as the facts themselves. Whether you are a defense attorney explaining your client’s actions or a prosecutor challenging them, you need an expert who integrates both events and decision-making processes. Dr. Black offers a unique approach, blending quantitative precision with qualitative insight into how individuals make sense of their world. he is a recognized expert with experience in international, federal, and state courts on lethal force, police use of force, officer-involved shootings, and civilian self-defense. He combines forensic analysis with human-centered perspectives, ensuring a balanced view that benefits both defense and prosecution.

Advanced Forensic Video and Qualitative Analysis

Video evidence often plays a pivotal role in determining the facts. Dr. Black is skilled in forensic video analysis, using Amped Five software to extract key details. What sets him apart is his ability to combine video analysis with qualitative thematic tools like Atlas.TI, understanding both what happened and how individuals interpreted their environment under stress.

Cognitive Interviewing and Human Performance Expertise

Dr. Black specializes in cognitive interviewing, exploring clients’ mindsets during critical moments leading up to the use of force. His approach bridges the quantitative analysis of human performance with qualitative insights into violent encounters, offering a comprehensive view of why actions were taken.

Military and Law Enforcement Expertise

With 30+ years in U.S. Army Special Forces and 23+ years in law enforcement, Dr. Black brings unmatched experience to each case. He provides practical insights grounded in real-world experience. His background ensures a comprehensive understanding of how policy, training, and decision-making intersect under pressure.

View Aragon National, Inc.'s Consulting Profile.

Donald L. Leach, II, is a Jail / Corrections Management expert with over 30 years of experience. He has 20 years of consulting experience on jail management issues nationally, focusing on Risk Management for Jails and Jail Operational Methodology. 

Mr. Leach has extensive supervisory experience, having overseen up to 402 employees (indirectly). He also supervised internal affairs investigations, experienced in interviewing, hiring, training, scheduling, motivating, evaluating, and dismissing personnel. He is experienced in administering and managing a large detention facility, developing and administering programs, budgeting, contract development and monitoring, conducting research, monitoring compliance with policies and procedures, community relations, public speaking, controlling costs, problem-solving, and preparing reports.

Litigation Support - Mr. Leach has served as an expert witness for 5 years, in both State and Federal court. His services are available to counsel for both Plaintiff and Defense and include case review, testimony, and consultation for jail and prison issues.

Areas of Expertise:

View Donald Leach's Consulting Profile.

My name is David T. Sweeney.  I am a Police Policy and Procedure expert and a retired 34-year veteran police leader with Seattle Police and Oregon State University PD.  I have decades of experience supervising a large number of police officers and supervisors. I am currently employed as adjunct faculty in the School of Police Staff and Command at Northwestern University. I enjoy assisting with expert reviews of policing best practices for a variety of legal standards for police departments. As an expert witness, I have been pleased to work with both plaintiff and defense attorneys. I will give you an honest assessment of your case, so that I can provide the best reports and helpful testimony. I have experience with 65+ total cases: 1/3 defense cases and 2/3 plaintiff cases.

Litigation Support - My goal is to improve best practices in policing by offering expert witness and police consultation services. I am also a trained mediator specializing in workplace conflicts. I provide honest, unbiased opinions. I will be happy to review and discuss your case. I will point out strengths and weaknesses of the case, and we can work on next steps, whether it be further case review, expert report, deposition, or trial testimony. I have spent 21 years as a sergeant and lieutenant, responsible for training and reviewing topics such as police pursuits, use of force, police tactics, de-escalation, police supervision, less lethal weapons, active shooter, SWAT, crowd control, legal standards, EEO, Human Resources, U.S. 1983 cases, and more.

 Areas of Expertise:

View David T. Sweeney's Consulting Profile.

Global Forensic Services, LLC (GFS) is a Forensic Consulting, Laboratory and Investigative Firm offering over 44 years of experience and training in a wide range of forensic science and private investigation disciplines.

Larry Stewart has personally examined tens of thousands of individual items of evidence from sources such as state, local, and federal agencies (e.g. Federal Bureau of Investigation, Secret Service, Bureau of Alcohol, Tobacco and Firearms, Central Intelligence Agency, and others), and foreign governments. On several occasions he has examined cases involving international disputes between governments. 

Mr. Stewart has testified as an Expert Witness in state, federal and military courts of law, as well as in foreign court systems to include; Austria, Australia, Canada, Germany, Singapore, Sri Lanka, Switzerland and Thailand. He has also testified at The Hague in the Netherlands and three times as an expert before the U.S. Congress. 

Areas of Expertise Include:

Mark J. Lang, MCJ, CPP, CHPA, is the Owner of Investigations HQ, LLC, a Florida-based law enforcement and security consulting firm. With more than 40 years of experience in Law Enforcement, Healthcare Security, and Security Management, Mr. Lang is recognized as an expert in negligent security, premises liability, hospital security, law enforcement practices, and police standards and procedures.

Mr. Lang retired from the Orange County Sheriff's Office (Florida) as a Captain assigned to the Special Investigations Division, where he supervised specialized units including Undercover Narcotics, Fugitive Apprehension, Criminal Intelligence, Vice, Pharmaceutical Investigations, and various federal and local task force operations. His extensive law enforcement career included leadership assignments in patrol, tactical operations, criminal investigations, and special operations.

Following his law enforcement career, Mr. Lang became the first Executive Senior Director of Security Operations for Orlando Health, one of the nation's largest healthcare systems. In this role, he was responsible for enterprise-wide security operations, workplace violence prevention programs, emergency management coordination, behavioral health security, and regulatory compliance. He is widely recognized for his expertise in hospital security management and healthcare workplace violence prevention.

Areas of Expertise:

Mr. Lang holds a Master of Criminal Justice degree from Boston University and a Bachelor of Arts in Criminal Justice Administration from Columbia College. He is board-certified as a Certified Protection Professional (CPP) through ASIS International and a Certified Healthcare Protection Administrator (CHPA) through the International Association for Healthcare Security and Safety (IAHSS).

Mr. Lang has consulted on more than 60 cases involving negligent security, premises liability, healthcare security, law enforcement practices, use of force, workplace violence, patient elopement, security operations, and police standards and procedures. He has provided expert analysis, case review, and report preparation throughout the United States. 

Norman D. Bates, Esq., President and founder of Liability Consultants, Inc., is a nationally-recognized expert in security and the law. For over forty years, he and his team of professionals have been providing security management consulting services to private industry as well as court-certified expert witness services nationwide to both plaintiff and defense firms in civil cases regarding inadequate security, negligent hiring or training, and workplace violence. Mr. Bates has presented seminars on civil liability issues and has authored numerous articles and books on the subject. Mr. Bates co-authored a publication on “The Prevention of Child Sexual Abuse in Youth-Serving Organizations” published by the National Center for Victims of Crime and the National Crime Prevention Council. 

BIOGRAPHY OF NORMAN D. BATES, ESQ. Formerly, Mr. Bates was an Assistant Professor of Criminal Justice at Northeastern University in Boston and Director of Security and Legal Counsel to the Saunders Hotel Corporation. He received his Juris Doctor degree from Suffolk University and a Bachelor of Science degree in Criminal Justice from Northeastern University. He is a member of the Massachusetts Bar, the International Association of Professional Security Consultants (President 2009-2011) and the National Crime Victim Bar Association.

Areas of Expertise:

Victor Lofgreen, PhD has over 30 years of experience and education in the fields of Corrections and Community Development. He is a prison and jail consultant who conducts cases analysis and develops reports to support litigation on prison and jail issues. Experience - Dr. Lofgreen has served as the CEO of a State Adult Correctional Institution and the Division Chief of a State Planning Agency for Corrections. He has authored numerous professional papers and articles on topics within his area of expertise as well as Agency Policy and Procedure Manuals and training materials. Litigation Support - Dr. Lofgreen's expertise is in Jail and Prison Policy and Procedures related to the standard of care for inmates by local, State, and Federal correctional agencies. His services are available to counsel representing plaintiff and defendant and include case review, case study and data analysis, report of Expert Opinion based on the evidence included in the case study, deposition, and trial testimony as needed. Areas of Expertise:

Lawrence R. Porte is a nationally and internationally recognized Investigative Analysis Expert and Trial Assist Analyst with more than forty (40) years of experience in federal law enforcement, protective intelligence, targeted violence assessment, aviation security, and criminal investigations.

Mr. Porte's distinguished career spans service with the United States Secret Service, the Department of Homeland Security, the Transportation Security Administration, higher education, and municipal law enforcement, giving him rare depth in both operational and analytical aspects of complex investigations.

 Litigation Support - Mr. Porte is widely respected for his ability to assess investigative integrity, identify behavioral warning signs, and provide clear, well-supported analyses. His current consulting work focuses on investigative case review, litigation assist support, and threat assessment for attorneys and institutions confronting high-risk or procedurally complex matters.

Areas of Expertise:

Background Experience - During his federal career, Mr. Porte held senior leadership positions with the United States Secret Service and later served as Special Agent in Charge for the Transportation Security Administration, where he directed investigative operations across a 14-state region that included approximately 110 federally protected airports. In that capacity, he supervised criminal investigations, cargo security matters, and internal misconduct inquiries, while also helping develop the TSA’s first Workplace Violence Policy and the agency’s Integrity Test Program aimed at combating theft and misconduct in airport environments.

Earlier in his career, Mr. Porte served on the White House Presidential Protective Division and was a member of the first White House Counter Assault Team, experiences that placed him at the center of some of the nation’s most sensitive protective and intelligence operations. He also opened and managed the Saginaw Resident Agent Office and later served as Special Agent in Charge of the Detroit Field Office, with oversight of additional Michigan offices.

Mr. Porte’s national and international recognition is further reflected in his participation in significant protective intelligence and investigative matters, including a threatened assassination plot involving Indian Prime Minister Rajiv Gandhi and an operation connected to extremist networks and coordinated activity extending into Canada. 

Timothy A. Dimoff, CPP, founder and president of SACS Consulting & Investigative Services, Inc. a leading security consulting firm, has over 40 years of experience in Law Enforcement and Security matters for both the public and private sectors. He is multi-certified in the security field and is considered one of the nation's leading authorities on negligent security procedures; security & vulnerability issues; police procedures and operations including use of force; high-risk workplace and human resource issues; narcotics investigations and enforcement. 

Mr. Dimoff is board certified by ASIS as a Certified Protection Professional (CPP?) which is internationally recognized as the “gold standard” certification for security management professionals, demonstrating their knowledge and competency in seven key domains of security.

Litigation Support - Mr. Dimoff has over 20 years of experience in testifying and consulting as an expert witness in over 500 cases and trials for both the plaintiff and the defense sides. His expert witness experience includes law enforcement procedures, security negligence of business or physical premises, human resources issues, meeting standards of practice in hiring and termination, employment practices, proper documentation, training, supervision, policies and procedures, harassment, discrimination, internal investigations, threats and excessive use of force.

Mr. Dimoff is a renowned speaker, trainer, and author who has offered expert commentary to national media including Dateline, NBC, CNN, The Chicago Tribune, The New York Times, The LA Times, The Washington Post, and The Wall Street Journal.  He is the author of four books, including How to Recognize Substance Abuse, The YOU in Business, and Life Rage, a chilling examination of societal rage and safeguards against it.

Mr. Dimoff holds a Bachelor of Science Degree in Sociology with an emphasis in Criminology from Denison University.

Areas of Expertise: 

View Timoth A. Dimoff's Consulting Profile.