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To build trust, forensic DNA labs must also embrace transparency

They’re important parts of the system but not immune from problems that have eroded trust

Medical Examiner

As law enforcement embraces advancing technologies, it is also essential to acknowledge their limits.

Bebeto Matthews/AP

This article is based on research conducted as a part of the CA POST Command College. It is a futures study of a particular emerging issue of relevance to law enforcement. Its purpose is not to predict the future; rather, to project a variety of possible scenarios useful for planning and action in anticipation of the emerging landscape facing policing organizations.

The article was created using the futures forecasting process of Command College and its outcomes. Managing the future means influencing it — creating, constraining and adapting to emerging trends and events in a way that optimizes the opportunities and minimizes the threats of relevance to the profession.

By Deputy Chief Andrew Jenks

For over 30 years, forensic DNA analysis has served as a powerful tool for identifying victims, suspects and missing persons, exonerating the innocent, and bringing closure to victims and their families. The effectiveness and reliability of this technology rests on the credibility of forensic DNA labs. Confidence in the police, however, is increasingly in question. As the criminal justice system and public place increasing trust in these laboratories to deliver accurate and unbiased results, transparency in the processes of forensic DNA labs is critical to the future of law enforcement.

Trust the science

Should we trust science? After all, science has eliminated diseases, provided clean water, created flying machines and brought us the internet. It has also brought pollution to our oceans and air and weapons capable of killing millions of people.

Confidence in science has fallen in America. A 2022 poll reported 39% of Americans say they have “a great deal of confidence” in the scientific community, compared to 48% in 2018 and 2021. [1] Along political lines, Democrats’ confidence in science dropped from 55% to 53%, while Republicans’ dropped from 45% to 23%. [1] Compounding the issue for forensic science is the diminished trust the public has in policing.

Law enforcement professionals have looked for scientific solutions to crime for decades. Phrenology, the 19th-century pseudoscience of examining the contours of a person’s skull, was used to predict criminal behavior. Phrenologists believed they could explain every criminal behavior, from petty theft to domestic violence to homicide. [2] The practice of phrenology has been discredited and discarded, but today there are still scientific practices used in law enforcement that cause controversy.

Fingerprint evidence, once considered the beacon of forensic science, has come under fierce scrutiny due to human error, bias and lack of standardization in collecting, examining and interpreting samples. [3] In the 2002 case U.S. v. Llera Plaza, Judge Louis Pollack ruled that fingerprint identification was not a legitimate form of scientific evidence, as it did not meet the Supreme Court’s standard for the admissibility of expert evidence. [4] While Pollack later reversed himself, some critics argue his original ruling was correct. [4]

Polygraph examinations, inadmissible in most civilian and military courts, [5] are still routinely used by law enforcement agencies in some criminal and most pre-employment background investigations. Like other forms of scientific inquiry, these examinations produce data; however, a trained professional most often must interpret that data to form a conclusion. It is also important to remember that science is a process that is continually evolving and improving, even as more precise ways to identify criminal suspects, like DNA analysis, emerge.

DNA and the police

Forensic DNA analysis is a relatively new field and an invaluable tool for law enforcement. The field is advancing quickly, with tools becoming more sensitive, accurate and affordable. As law enforcement embraces advancing technologies, it is also essential to acknowledge their limits.

Deoxyribonucleic acid, or DNA, is a molecule that carries genetic information for the development and functioning of an organism. DNA consists of two linked strands that wind around each other to resemble a twisted ladder — a shape known as a double helix. [6] Analyzing DNA evidence begins with the collection of biological material such as blood, saliva, semen or vaginal fluid. Biological evidence may also be collected from objects. When a person handles an object, skin cells and cellular debris containing DNA are often left behind.

Authors Suzanne Bell and John M. Butler describe the analysis of forensic DNA evidence in their 2022 book, “Understanding Forensic DNA.” According to Bell and Butler, once biological material is collected, the DNA is extracted from its source and measured. Specific regions of this DNA are copied in a process known as polymerase chain reaction (PCR), creating millions of copies for each DNA segment. The standard for human DNA typing is short tandem repeat (STR) analysis or forensic analysis, which evaluates specific regions found on DNA. STRs are inheritable marks in a series of 2–7 bases. These bases are repeated in various ways in each person. The variable nature of the analyzed regions increases the discrimination between one DNA profile and another. The likelihood that two individuals who aren’t identical twins would have the same DNA profile can be as high as one in a billion or more. Y chromosome analysis is also standard practice. Y chromosome analysis is useful when a mixed sample is discovered to separate biological male DNA from biological female DNA. [7]

Once a DNA profile is created, the laboratory technician may enter it into the National DNA Index System (NDIS) or compare it directly with a provided sample from an arrestee or suspect. Launched in 1998, NDIS is a clearinghouse for DNA profiles used by every state and U.S. territory. It uses the Combined DNA Index System (CODIS) software to compare case-to-case or case-to-offender/arrestee profiles. NDIS is a network of linked systems managed by the FBI that contains profiles from local and state databases. It contains several indexes within these databases, including the Offender Index, containing people convicted of various crimes; the Arrestee Index, people arrested for committing specific felonies; the Forensic Index, profiles from crime scenes; and the Missing Persons Index, profiles from unidentified persons or reference samples from relatives of missing persons. [8] The CODIS system uses algorithms to compare samples and create leads for law enforcement or identify potential assailants.

It is essential to point out that DNA evidence does not solve crimes; thorough and proper investigations solve crimes. DNA analysis is a tool for investigators that can be used to include or exclude individuals. While it is a powerful tool, DNA evidence is not infallible. Despite common perceptions, the police cannot determine if every DNA profile is unique. The chances of randomly selected people having the same DNA profile are extremely small, but comparisons are still discussed as probabilities and not certainties. In addition, the presence of DNA evidence is not proof of guilt. How the DNA sample arrived at the location is as important as to whom the sample belongs.

Traditional detective work is still the backbone of any criminal investigation. One of the most critical details in contemporary policing is the effectiveness of the crime lab charged with examining the physical evidence.

Challenges of DNA lab operations

Forensic DNA analysis has been used in law enforcement for over three decades. Improvements in research and technology are revolutionizing forensic science, improving the quality of evidence, collection of evidence and investigations, and advancing a fairer justice system. DNA analysis is evolving with advanced techniques that provide more detailed information from samples. Rapid DNA technology allows for profiles to be obtained in hours, not days. Recent research looks to provide physical features such as hair and eye color, race and facial features. [9] A University of Florida study discovered DNA samples floating through the air, suggesting that one’s breath can provide evidence. [10] The Forensic and National Security Sciences Institute at Syracuse University has developed a machine learning approach, or artificial intelligence, to enhance the efficiency and accuracy of DNA analysis and improve the interpretation of complex DNA profiles. Its process enables rapid and automated separation of DNA to analyze mixed samples. [11] Despite the expanding use of AI and more precise collection, human factors can still err and destroy the public’s confidence in DNA.

The Washington, D.C. Department of Science crime lab is a cautionary tale of what can happen if standards fail. The D.C. lab lost its accreditation in 2021 when it was discovered mistakes were being covered up, and the accuracy of evidence analysis came into question. Additional audits and reports uncovered more issues, and attempts to regain accreditation have failed because the lab has been unable to demonstrate improvements in processes. [12] As a result, the lab has had to rely on outside contractors to process evidence samples and review a decade’s worth of convictions that relied on evidence analyzed by the lab. The U.S. attorney’s office, which prosecutes local felonies in D.C., declined to bring charges in two-thirds of all arrests, mostly drug offenses, made by the D.C. police in 2022 due to the lab being unable to perform forensic testing. [13] An audit in 2022 found the lab failed to act as an independent part of the justice system, failed to comply with its policies and did not maintain adequate resources to function as a crime lab. District officials have pointed to the essentially nonfunctioning crime lab as an obstacle to improving public safety, costing the district millions of dollars. They expected in early 2023 it would take at least until 2024 to reopen. [12]

The D.C. lab story is not an anomaly. Labs across the country, including the San Diego Regional Crime Laboratory and Houston Police Department Crime Lab, have experienced similar issues. [14,15] The credibility of forensic science is shaped by public opinion as much as well-practiced science. If labs continue to suffer from poor internal controls and sloppy practices, scientific integrity is at risk, and the criminal justice system suffers.

The future of forensic DNA analysis depends on a commitment to excellence. In most cases, problems in the troubled laboratories resulted from human error, not inaccurate science. In San Diego, auditors found security at the lab did not meet FBI standards; former employees and temporary contractors still possessed active keycards years after leaving the lab. [15] Internal audits documented insufficient technical reviews of forensic analysis and unintentional switching of DNA samples. [15]

The Houston Police Department Crime Lab suffered from decades of underfunding, mismanagement, a massive backlog of sexual assault evidence, and reports of fraud and negligence by lab employees. [16] In 2014 it was overhauled. The lab became independent from the police department and was reborn as the Houston Forensic Science Center. Once considered the worst crime lab in the country, the HFSC is now a model forensic science laboratory. [16] Due to these instances and others, the move to improve scientific standards in forensics is being embraced by the forensic community, legal advocates and law enforcement. It has the potential to address the challenges presented here. [14]

Oversight and beyond

It is important to emphasize that most forensic DNA laboratories are staffed by professional scientists and technicians who adhere to the best practices and federal accreditation standards. All criminal forensic DNA laboratories in the United States must meet standards set by the FBI through accreditation. [8] The two prominent accrediting agencies that ensure labs meet FBI criteria are the American Association for Laboratory Accreditation and the ANSI National Accreditation Board. While accreditation is mandatory for forensic DNA labs, it is not for other forensic science disciplines, including crime scene evidence collection, fingerprint analysis and blood-spatter analysis.

In 2009 the National Academy of Sciences (NAS) released a revolutionary report, “Strengthening Forensic Science in the United States: A Path Forward.” The report concluded that except for DNA analysis, many forensic techniques were not scientifically valid. It called for more research into these disciplines and the independent oversight and standardization of their use. [17] The NAS report is considered a blueprint for what an unbiased, legitimate forensic laboratory should be, and its recommendations have been implemented with successful results, including at the HFSC. [16]

The distinction between accredited forensic DNA labs and nonaccredited forensic science, however, is not considered by many in the criminal justice system, including jurors. Despite this reality, it is critical that standards for all laboratory practices be scientifically supported. Oversight and accreditation are essential to improve and maintain public trust in forensic science, but a more proactive approach is also necessary.

An ideal forensic DNA lab prioritizes accuracy, reliability, ethical considerations, transparency and accountability. It is appropriately staffed with highly trained forensic scientists and technicians and works to eliminate human bias and errors wherever possible. This lab is accredited in forensic DNA and all forensic disciplines it conducts. It seeks to be as technologically advanced as possible while remaining cautious before implementing the newest tools. It also collaborates with local law enforcement while remaining impartial and independent to prevent conflicts of interest. The ideal forensic lab is dedicated to maintaining the highest standards by maintaining accreditation standards, following internal policies and regularly conducting internal audits.

Interestingly, these suggestions are nothing new and can largely be found in the 2009 NAS report. One issue, though, is not in the report: Beyond a commitment to standards and oversight, an ideal lab recognizes the need for community outreach and engagement through proactive transparency.

Many law enforcement agencies have begun to realize the need to tell their stories through social media. The days of responding to media questions with the old “It’s under investigation” are over. Trust in the police has declined from 82% in 2020 to 72% in 2022. [18] In addition to public information officers, many agencies now employ full-time media relations experts who ensure police practices are transparent and accountable. Forensic laboratories should do the same. Transparency and accountability create trust and credibility, which are essential to supporting a functioning criminal justice system. [19]

How to achieve transparency

My own research into the future of forensic DNA, including a panel of experts convened to study transparency in forensic sciences convened in April 2023, emphasized the importance of maintaining accreditation standards, fair reporting by the media, ensuring public confidence and continued research in DNA-related technologies. Surprisingly, public opinion was rated as important to the future of forensic DNA as maintaining scientific standards, pointing to the need for transparency.

Transparency involves being open, straightforward, honest and easily understood. Forensic DNA labs will build trust with the public and improve their credibility by using available media, including social media, to educate, explain, respond to concerns and help their communities understand the realities of the science. Rather than being at the mercy of the media, forensic science leaders will benefit from actively educating the public about their policies, practices and procedures.

Study of the labs with deficits that have led to a loss of trust in police can help elicit best-practice recommendations for others in forensic labs. They are:

  • Employ media professionals: Media relations specialists working for laboratories can help tell a story of forensic DNA analysis that is easily understood and educates the potential jury pool. Providing public access to nonconfidential information, such as lab practices, successful investigations and challenges, fosters accountability while improving credibility.
  • Mandate accreditation for all forensic laboratories: Accountability goes hand in hand with transparency. A commitment to maintaining the highest standards is essential for the future of forensic science. All forensic DNA laboratories in California are accredited by the ANSI National Accreditation Board or American Association for Laboratory Accreditation. However, accreditation for forensic labs that do not conduct DNA analysis is optional. Requiring accreditations for all forensic laboratories will ensure consistent standards and practices across the field, improving accuracy, limiting human error and improving public confidence.
  • Collaboration: Law enforcement leaders should work with leaders in the forensic science community to advance mutual goals while maintaining professionalism and independence. Truth, fairness and unbiased investigations are a common goal. Successes should be celebrated, while errors should be openly acknowledged and corrected. By working together to communicate all investigative processes, law enforcement agencies and forensic laboratories can provide the public with the transparency it expects.


Media reports of widespread police misconduct have, fairly and unfairly, eroded public trust in the police and criminal justice system. As a result, many agencies have taken a proactive, community-engaged approach to law enforcement. The principles of procedural justice, giving people voice, respect, neutrality and trustworthiness, are widely implemented to bring police agencies and communities together.

Forensic DNA laboratories should take the same approach by embracing transparency to improve public trust. Trust and confidence in the criminal justice system are essential to maintain public order. To ensure that is the case, all forensic laboratories should be accredited to standardize the science. Building positive community relations while ensuring standards are maintained by all involved will result in greater confidence in the evidence and a fairer and more just justice system for all.

1. Burakoff M. Confidence in science fell in 2022 while political divides persisted, poll shows. AP News. June 2023.

2. Ziegner K. Phrenology and inmate healthcare. The NYC Criminal. November 2015.

3. Lynch C. The problem with forensic sciences. Discover. November 2022.

4. Mnookin JL. Fingerprints: not a gold standard. Issues in Science and Technology. Fall 2003.

5. United States v. Scheffer, 523 U.S. 303 (1998). Justia. 1998.

6. Green E. Double helix. National Human Genome Research Institute. December 2023.

7. Freeman S. How DNA profiling works. How Stuff Works. November 2023.

8. Bell S, Butler JM. Understanding forensic DNA. Cambridge University Press. September 2022.

9. Greenwood M. The future of forensic DNA analysis. AZoLifeSciences. January 2022.

10. Whitmore L, McCauley M, Farrell JA, et al. Inadvertent human genomic bycatch and intentional capture raise beneficial applications and ethical concerns with environmental DNA. Nature Ecology & Evolution. May 2023.

11. Bernardi D. Forensic scientists design the first machine learning approach to forensic DNA analysis. Syracuse University News. July 2021.

12. Grablick C. D.C.’s troubled crime lab won’t be accredited until at least 2024. DCist. February 2023.

13. Moore J. DC’s top prosecutor says lack of testing from shuttered crime lab to blame for some dropped cases. WTOP. May 2023.

14. Garrett BL. Policing forensic evidence. American Journal of Law and Equality. 2022.

15. Moran G. San Diego crime lab lapses come to light. San Diego Union-Tribune. November 2021.

16. Stout P. The secret life of crime labs. PNAS. October 2023.

17. Ten years later: The lasting impact of the 2009 NAS report. Innocence Project. February 2019.

18. Brown R. Do we trust the police?. Psychology Today. April 2023.

19. Passalacqua NV, Pilloud MA, Belcher WR. Scientific integrity in the forensic sciences: Consumerism, conflicts of interest, and transparency. Science & Justice. September 2019.

About the author

Andrew Jenks has over 23 years of law enforcement experience and has worked for the Glendale (California) Police Department since 2002. He holds a Bachelor’s degree in English from California State University, Northridge, and a Master’s degree in Social Work from California State University, Long Beach. Andrew was promoted to the rank of Deputy Chief in April 2023. He oversees the Professional Standards Bureau, Training Bureau, the Transparency, Audits and Accountability Bureau and assists the Chief in the day-to day operations of the police department. Andrew is a graduate of California POST Command College class 71.