Firearms Expert Witnesses: 9

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.

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.

Daniel G. O'Kelly has over 46 years of experience as a range instructor, firearm designer, builder, auditor of licensees, collector, and expert on firearms and ammunition. 

Mr. O'Kelly served for 11 years as a Police Officer and for 23 years as a Special Agent for the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). As one of ATF’s leading firearm experts, he was Lead Instructor of Firearm Technology at the ATF National Academy. Since his retirement from the ATF, he has served as a Senior Corporate Manager for Cabela’s, the then largest firearm retailer in the world, where he co-developed a firearm technology and ATF compliance training program for that company, and is the Founder/Director of IFSA. 

Mr. O'Kelly then founded and is the Director of, the International Firearm Specialist Academy (IFSA), a guild of award-winning experts, former Federal Agents, Investigators, Police Officers, Medical Doctors, and an Attorney, in the Firearm and Forensics field.

Litigations Support -  Mr. O'Kelly has testified continually in depositions and in criminal & civil cases in State, Superior, Circuit, District and Federal Courts since 1978, and has been recognized as an expert witness in Federal and State courts since 1990. He has opined on the topics of:

 Noteworthy Cases

• Retained as Defense expert in the Alec Baldwin case.
• Testified in four Federal trials on the topic of federal firearm definitions from 2014 to 2019 which resulted in ATF undertaking a 2-5 year rewrite of the definition of a firearm “frame or receiver”, which reached a SCOTUS decision in 2022. 
• Testified in trials wherein 1289 items of firearm-related evidence were ruled out by the Court as a direct result of his testimony.
• Worked undercover in three international illicit arms dealing cases, including the Diveroli case which sparked the movie "War Dogs", and is one of two ATF Agents to ever perform an undercover investigation of illicit international firearm trafficking in Europe.   

View Daniel O'Kelly's Consulting Profile.

Kirk DeLeeuw is a highly regarded and accomplished Forensic Biology and DNA Consultant / Expert Witness both nationally and internationally. He has over 20 years of dedicated experience in Molecular Biology and Forensic Science and is well respected worldwide.

Mr. DeLeeuw's career is defined by a deep technical mastery of DNA analysis, including specialized expertise in interpreting complex multi-contributor samples using Probabilistic Genotyping Software (PGS) such as STRmix. Mr. DeLeeuw is licensed by the Texas Forensic Science Commission. He likewise has a comprehensive understanding of FBI Quality Assurance Standards (QAS) and ISO/IEC 17025 accreditation requirements. He applies the standards through meticulous auditing of case files, bench notes, and high-volume electronic data files and images.

Litigation Support - Beyond the laboratory, Mr. DeLeeuw is a seasoned Expert Witness, qualified to provide testimony in Body Fluid Identification / Serology and DNA Analysis across numerous jurisdictions. He has provided sworn affidavits and oral testimony in federal, circuit, and district courts in many states including Washington DC, and internationally in the Royal Turks and Caicos Islands. His ability to translate sophisticated molecular biology data into clear, accessible testimony ensures that scientific integrity remains paramount during both civil and criminal litigations.

Mr. DeLeeuw maintains technical proficiency through a rigorous commitment to continuing education, frequently attending the International Symposium on Human Identification and National CODIS Conferences. His hands-on experience spans a wide array of instrumentation, including Applied Biosystems Genetic Analyzers and Hamilton robotic workstations, as well as various quantification and amplification kits. This combination of technical expertise, regulatory knowledge, and proven courtroom experience allows him to provide unparalleled oversight and analysis in the field of forensic DNA.

Areas of Expertise:

Background Experience - Mr. DeLeeuw's extensive professional background includes high-level roles across private and public sectors. As a Forensic DNA Analyst at DNA Labs International, he analyzed casework from across the United States and internationally, utilizing advanced PCR/STR-based methods and various chemistries. Prior to that, he served for nearly 20 years as a Forensic Scientist for the Michigan State Police.

Ryan Larrison is a senior forensic science and public sector executive with over 25 years of experience spanning Forensic Laboratory Operations, Quality Assurance, Firearms Examination, and large-scale Program and Systems Management within the Michigan Department of State Police.

Mr. Larrison currently serves in a senior leadership role within the Information Technology Division, where he directs a multi-million-dollar portfolio of enterprise systems, operations, and project delivery. In this capacity, he oversees complex, multi-agency initiatives, aligning technical execution with operational and investigative outcomes across multiple state departments. His work includes executive sponsorship of statewide technology programs and the coordination of vendors, stakeholders, and cross-functional leadership teams in high-risk, high-visibility implementations.

Litigation Support - Mr. Larrison serves as an expert witness in cases involving laboratory analysis or laboratory quality assurance. He has been deposed and/or testified over 200 times in the past 5 years.

Areas of Laboratory Expertise:

Background Experience - Prior to his current role, Mr. Larrison served as Assistant Division Director and Quality Assurance Manager for the Michigan State Police Forensic Science Division. In that role, he was responsible for the strategic direction, implementation, and oversight of quality systems across seven accredited forensic laboratories. He led all quality assurance activities, including training, corrective action programs, risk assessment frameworks, and accreditation compliance under ISO 17025 standards. His leadership resulted in a substantial reduction in non-conformities and sustained accreditation across all laboratory operations. 

Mr. Larrison has extensive experience as a program executive and project sponsor for complex forensic and evidential systems. He directed the statewide implementation of the Evidential Breath Alcohol Testing Program, including instrument selection, software integration, vendor coordination, and regulatory compliance, supported by a $2.5 million procurement process. He also led the development and implementation of a Forensic Genetic Genealogy program, establishing quality expectations, vendor deliverables, and investigative reporting standards.

Dean S. Molnar, Jr. is a highly trained and exceptionally experienced Firearm and Tool Mark Examiner, Crime Scene and Firearms Trajectory Analyst, and a proven leader in the field of Forensic Science Operations and Quality Assurance. Mr. Molnar has over 25 years of experience as a certified law enforcement officer and State Trooper, and over 17 years of experience serving as a firearm and tool mark examiner, firearms and tool mark unit supervisor, and laboratory director with the Michigan State Police (MSP) Forensic Science Division.

Litigation Support - Mr. Molnar's experience as a forensic firearm and tool mark examiner includes recognized expert testimony in over 140 criminal cases in both state and federal courts involving both firearms and tool mark identification, crime scene investigation, and shooting reconstruction.  He has personally processed over 60 homicide scenes during his career, including scenes involving shooting reconstruction, photography, and documentation.

Areas of Expertise:

• Firearms function, operability, alterations, defects, conversions, modifications, accidental discharge
• Cartridge manufacture and source determination of ammunition components
• Shooting scene (trajectory) reconstruction
• External and/or terminal ballistics calculations and determinations of the projectile’s trajectory, ricochet, penetration, etc
• Distance determinations (muzzle-to-target determinations) from gunshot residue patterns or shot pellet patterns
• Serial number restorations (firearms, motorcycles and other vehicles, bicycles, etc.) – anything with an identifying characters, numbers or markings that have been obliterated either intentionally or by wear or corrosion

Background Experience - Mr. Molnar’s leadership experience has included firearms unit supervisor duties at three different laboratories. He currently serves in a key role as the Laboratory Director at the Michigan State Police-Lansing Laboratory where he is specifically assigned as the operations director for pattern disciplines.

Mr. Molnar also has over seven years of quality assurance experience as an ANSI National Accreditation Board (ANAB) assessor. His years of experience include almost 15 years of ongoing training within an extremely professional and accredited crime scene processing program at MSP, along with even more specialized training in firearms trajectory analysis. Mr. Molnar holds a Bachelor of Science in Fire Science and a Bachelor of Science in Criminal Justice from Lake Superior State University. He is a long-time member of the Association of Firearms and Tool Mark Examiners (AFTE) and is also a member of the American Society of Crime Laboratory Directors (ASCLD).

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.

Emanuel Kapelsohn is an internationally recognized Firearms Training and Use of Force consultant who has instructed thousands of police and security officers, federal agents and others throughout the U.S. and abroad since 1980. A graduate of Yale University and Harvard Law School, he is a practicing attorney in addition to his consulting work. 

As vice president of the Internat’l Assoc. of Law Enforcement Firearms Instructors, Mr. Kapelsohn is a certified in force science and shooting scene reconstruction, and as an instructor in numerous law enforcement disciplines. He is a featured presenter at national and international instructor conferences. He has authored over 130 published articles, is Associate Editor of "Standards & Practices Guide for Law Enforcement Firearms Instructors," and principal author of "Firearms Training Standards for Law Enforcement Personnel," and "Guidelines for Simulation Training Safety." 

Mr. Kapelsohn testifies as an expert witness in civil and criminal cases in state and federal courts nationwide, and has testified by invitation before both houses of Congress. 

Testimony on the Following Subjects:

View Emanuel Kapelsohn's Consulting Profile.

Internationally recognized expert on Firearms History and Values. Consulting, appraisals, expert witness services, and museum exhibit design. Retired director of NRA Museums Division, overseeing 3 national firearms museums & curating NRA's 10,000 gun collection.

Writing & Media - Editor of leading price guide Standard Catalog of Firearms. Author of hundreds of articles and nine firearms books.  200+ national TV appearances as Gun Expert.

Attorney (inactive)  J.D.  AGI certified firearms appraiser.