DNA Evidence in Criminal Investigations: Uses and Limits
This paper examines the role of DNA evidence in criminal investigations, weighing its benefits against its significant limitations. It discusses how DNA has been used to exonerate wrongfully convicted individuals while also noting how it can be fabricated or transferred inadvertently to implicate innocent people. The paper addresses research showing that jurors tend to regard DNA evidence as 95% accurate—an overestimation that can distort verdicts. It also considers the ethical challenges of DNA profiling, the patchwork of state laws governing prisoners' access to DNA testing, and the Supreme Court's ruling that inmates have no constitutional right to such testing. The paper concludes that DNA evidence is a valuable but imperfect tool that must be handled with scientific rigor and appropriate skepticism.
- Introduction: Controversy surrounding DNA evidence in criminal cases
- Why DNA Use Is Important in Criminal Investigations: DNA as a tool for exoneration and suspect identification
- Why DNA Use Is Problematic: Fabrication risks, secondary transfer, and jury overconfidence
- Where the States Stand: State laws and Supreme Court rulings on DNA testing rights
- Conclusion: DNA evidence as valuable but imperfect investigative tool
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What makes this paper effective
- Maintains a balanced, two-sided argument throughout — acknowledging DNA evidence as valuable while systematically identifying its vulnerabilities, which prevents the essay from reading as one-sided advocacy.
- Grounds abstract claims in concrete cases, such as Bruce Godschalk's exoneration and Lukis Anderson's wrongful implication through secondary DNA transfer, giving the reader clear real-world anchors.
- Draws on a range of source types — legal reporting, peer-reviewed psychology research, and forensic science journalism — lending the argument interdisciplinary credibility.
Key academic technique demonstrated
The paper uses the concession-and-rebuttal structure effectively within each section. It concedes a strength of DNA evidence (exonerations, accuracy relative to other forensic methods) before pivoting to a limitation (fabrication, secondary transfer, jury overconfidence). This dialectical approach models how to handle complex evidence-based topics without false certainty.
Structure breakdown
The paper opens with an introduction that frames the controversy and previews both sides. Two body sections address the positive and negative dimensions of DNA usage in turn. A third body section narrows to legal and policy context at the state level. The conclusion synthesizes all threads and offers a measured normative claim about how DNA evidence should be treated within the criminal justice system. The structure follows a classic analytical essay format appropriate for undergraduate legal or criminology courses.
Introduction
The use of DNA evidence in criminal investigations remains somewhat controversial even though the technology exists to utilize this tool in every relevant case. Part of the reason it is controversial is that, if applied broadly, it could overturn hundreds of cases in which DNA evidence was not permitted at trial — potentially exonerating defendants, as in the case of Bruce Godschalk, who was convicted of rape in 1986. Years later, DNA testing proved that Godschalk was not the rapist (Krieger, 2011). On the other hand, DNA evidence is viewed with considerable suspicion by those who distrust the process or doubt that DNA evidence is reliably protected through a chain of custody.
For example, Austin (2015) notes that "scientists in Israel have demonstrated that it is possible to fabricate DNA evidence, undermining the credibility of what has been considered the gold standard of proof in criminal cases." So while DNA evidence can help defendants, it can also be used to frame them. Worth (2018) states that "we leave traces of our genetic material everywhere, even on things we've never touched. That got Lukis Anderson charged with a brutal crime he didn't commit." As The Marshall Project points out, secondary transfer of DNA made it appear that Anderson, a homeless person, was guilty of killing an elderly person he had never met.
Because DNA is a complex matter that still requires sound scientific understanding, this paper discusses both the positive and negative aspects of using DNA in criminal investigation.
Why DNA Use Is Important in Criminal Investigations
The science of criminal investigation and criminology has advanced considerably. Today, criminal investigators have a number of tools at their disposal to help solve crimes, including psychological profiling, geographical profiling, victim profiling, and DNA profiling. DNA acts not only as physical evidence that can potentially verify an account of what happened at a crime scene — it can also serve as a source of information for profiling. A DNA database functions much like a fingerprint database, containing information that can link suspects to specific crimes while exonerating others. In a rape case, for example, if DNA is collected at the scene it could match a profile in the database and identify a suspect that investigators can then build a case around.
DNA use can help set the record straight. For innocent persons convicted of crimes they did not commit, DNA evidence has been used to secure exoneration. Many others still await the opportunity to pursue DNA testing to prove they were not at the scene of the crime (Krieger, 2011). In cases where it is difficult to determine whether a suspect was present at a crime scene, DNA usage can be instrumental in making or breaking the case.
Worth (2018) states that "DNA is the most accurate forensic science we have. It has exonerated scores of people convicted based on more flawed disciplines like hair or bite-mark analysis. And there have been few publicized cases of DNA mistakenly implicating someone in a crime." This does not mean that DNA usage is 100% accurate in every case — it is simply one more tool that criminal investigators can rely upon. It should never be used to tell the whole story, just as no case should depend solely on a single witness. "Like most human enterprises, DNA analysis is not perfect. And without study, the scope and impact of that imperfection is difficult to assess," says Peter Gill, a British forensic researcher (Worth, 2018).
Why DNA Use Is Problematic
As evidence, DNA is not above being tampered with — yet juries tend to respect it almost unconditionally. Lieberman, Carrell, Miethe, and Krauss (2008) found that jurors view DNA evidence as approximately 95% accurate and highly indicative of guilt or innocence. This is problematic because DNA is simply not that conclusive. As noted above, it can be helpful — but it should not be treated as the ultimate arbiter of truth. The case of Lukis Anderson illustrates this point: the DNA found at the crime scene was not his, but it was made to appear as though it were, and investigators built their narrative around that DNA profile (Worth, 2018).
DNA transfer specialists argue that the level of faith placed in DNA evidence in criminal investigations must be substantially reduced. "The criminal justice system must be willing to question DNA evidence," and forensic scientists — not law enforcement officers — should be the ones overseeing the transfer and analysis of DNA evidence (Worth, 2018). Systemic corruption enters through small gaps, much as water follows the path of least resistance. Unless the system places control and interpretation of evidence in the hands of qualified experts, DNA evidence can become a tool for constructing false narratives in order to secure convictions. Few people appreciate how easily DNA can travel between individuals — potentially traveling as far as a fly might carry it — yet criminal investigators often simply identify the source of the DNA without asking how it came to be where it was found.
As a profiling tool, DNA evidence also carries limitations, particularly regarding the ethics of profiling (Williams & Johnson, 2006). Profiling, regardless of the data sets it relies upon, is not governed by a uniform standard of operation. Many profilers work according to their own methods, and some in criminal justice doubt profiling's efficacy altogether. DNA profiling is no exception. While it can be useful in building databases and serving as a guide, treating it as a completely objective science free of any subjective interpretation would misrepresent how it actually functions. Furthermore, the lack of educational standards and guidelines surrounding the use of profiling makes its application ethically questionable (Kocsis, 2003).
DNA profiles can also be effectively "hacked" to construct a false narrative, as Israeli scientists have demonstrated: "The scientists fabricated blood and saliva samples containing DNA from a person other than the donor of the blood and saliva. They also showed that if they had access to a DNA profile in a database, they could construct a sample of DNA to match that profile without obtaining any tissue from that person" (Austin, 2015). Constructing a DNA sample to match a criminal case profile is equivalent to falsifying evidence. DNA evidence can therefore be planted, just as any other type of evidence can be, and should not be viewed as foolproof.
Conclusion
DNA usage can be effective in helping cases, and it can also be exploited, just like any other type of evidence in a criminal investigation. It can be used by the accused to argue for innocence, and it can be used by the prosecution to argue for guilt. It can be used by forensic scientists to construct profiles, and it can be used improperly to falsify evidence and fabricate a narrative. The Supreme Court has stated that inmates do not have a right to have states' DNA evidence admitted for testing, but most states do have laws indicating the extent to which prisoners may access DNA testing to help clear their names.
Ultimately, DNA evidence should be treated like any other form of evidence — valuable, but not beyond the possibility of tampering. For that reason, it can be neither wholly relied upon on its own nor wholly dismissed. Under the right to due process, the defense should be permitted access to DNA testing when it may bear on their case. And criminal investigators should approach DNA evidence cautiously and carefully, so that if they do use it to prosecute, they can demonstrate that the evidence has not been tampered with and that it factually links the accused to the crime.
References
Austin, E. (2015). DNA evidence can be faked. Retrieved from https://www.forensicmag.com/news/2015/02/dna-evidence-can-be-faked
Kocsis, R. N. (2003). Criminal psychological profiling: Validities and abilities. International Journal of Offender Therapy and Comparative Criminology, 47(2), 126–144.
Krieger, S. A. (2011). Why our justice system convicts innocent people, and the challenges faced by innocence projects trying to exonerate them. New Criminal Law Review, 14(3), 333–402.
Lieberman, J. D., Carrell, C. A., Miethe, T. D., & Krauss, D. A. (2008). Gold versus platinum: Do jurors recognize the superiority and limitations of DNA evidence compared to other types of forensic evidence? Psychology, Public Policy, and Law, 14(1), 27.
Liptak, A. (2009). Justices reject inmate right to DNA tests. Retrieved from https://www.nytimes.com/2009/06/19/us/19scotus.html
Williams, R., & Johnson, P. (2006). Inclusiveness, effectiveness and intrusiveness: Issues in the developing uses of DNA profiling in support of criminal investigations. The Journal of Law, Medicine & Ethics, 34(2), 234–247.
Worth, K. (2018). Framed for murder by his own DNA. Retrieved from https://www.themarshallproject.org/2018/04/19/framed-for-murder-by-his-own-dna
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