Why DNA Retention Matters
Several major cold cases, such as the Golden State Killer, were solved in recent years through DNA, bringing elusive killers to justice thanks to breakthroughs in technology and the availability of websites such as GEDmatch and direct-to-consumer DNA testing kits.2
As a result, DNA collection and retention policies are more necessary than ever and will change the landscape of criminal justice. The discussion involves two negative concerns and two significant benefits worth examining carefully.
The Issues: Four Arguments
Although the collection of DNA from arrestees has been deemed constitutional by the U.S. Supreme Court, concerns about collection and retention remain.3 DNA is typically treated by courts comparably to fingerprinting and found constitutional as decided in United States v. Pool.4
In Justice Scalia’s dissent, he cited concerns about the government placing citizens’ DNA into a database indefinitely, whether the arrest was legal or illegal in nature. This loophole requires attention to ensure that innocent parties do not have their Fourth Amendment rights infringed upon by DNA collected during unlawful stops or arrests.
DNA genealogy websites are incredibly popular, offering users the chance to explore their ancestry. These sites are increasingly of interest to law enforcement, with dozens of unsolved cases sitting on shelves with DNA but no database matches.7
Joseph DeAngelo, the Golden State Killer, was tracked down through GEDmatch, the only site that allows law enforcement to actively search its database in this manner. Ancestry.com and 23andMe maintain tighter controls, releasing data only under court order.8 GEDmatch now uses an opt-in policy so that only consenting users’ data can be accessed by law enforcement.
The Department of Justice issued an interim policy requiring police to identify themselves when uploading data in hopes of locating a suspect’s relatives, rather than remaining anonymous.10 That policy relies solely on officer accountability, which is a significant limitation.
The Golden State Killer case demonstrates what is possible. Joseph DeAngelo was a heinous rapist and murderer, responsible for twelve deaths and fifty rapes.11 His DNA was retained from crime scenes over decades but was never in law enforcement databases because he was never a suspect. Investigators turned to GEDmatch, identified possible relatives through partial matches, and used genealogical research to narrow the pool to DeAngelo.
This case, alongside Maryland v. King, demonstrates the significant value in law enforcement obtaining and retaining a large database of DNA samples for comparison against incoming or previously convicted offenders. CODIS, which came from the DNA Identification Act, was designed as exactly this: a nationwide database to store samples from crime scenes, convicted offenders, unidentified remains, and voluntarily provided samples from relatives of missing individuals.12
The primary difference today is that DNA technology has advanced significantly, putting testing kits in consumers’ hands. By allowing users to opt in, privacy concerns can be substantially mitigated.
A strong benefit of retaining DNA is its active contribution to exonerating the wrongfully convicted. If DNA evidence from a crime scene cannot be located or was thrown out, exoneration becomes impossible. This harms the wrongfully convicted and diminishes the chance of justice for victims and their families.
The Innocence Project has seen significant success exonerating falsely convicted people through post-conviction DNA testing, including individuals on death row.13, 14 DNA that was not retained, deteriorated, or depleted through repeated testing cannot be used for exoneration. A processed digital database preserves the information indefinitely.
Year after year, rape kits sit unprocessed on shelves. Retaining DNA from lawful arrests in a database, rather than as physical samples, ensures that even an unprocessed kit could match against an existing database entry. Processing DNA evidence as high priority frees up evidence room space, prevents deterioration, and gives victims and their families peace of mind that the sample is safe and available for comparison.
Retaining processed DNA in a database also prevents the problem of sample depletion, as seen in the Golden State Killer investigation, where testing a single finite sample multiple times risks exhausting it. Storing processed results digitally ensures the information is safe and may hold the key to solving decades-old crimes.
Conclusion
Privacy and Fourth Amendment rights must be taken seriously in any DNA retention policy. The loophole created by Maryland v. King around unlawful arrests, and the third-party doctrine’s application to genealogy websites, require legislative attention. These are real concerns, not hypothetical ones.
At the same time, the case for robust DNA retention is compelling. Cold cases solved. Wrongful convictions overturned. Rape kits that have been sitting untested for years finally matched to perpetrators. It is up to agencies to develop strong, fair policies and secure the funding to make DNA testing a central strategy rather than an afterthought.
All journal reference materials for this paper were obtained from the Purdue University Global library, including both peer and non-peer reviewed sources. The Innocence Project was cited within one journal source. Two sources, a Rolling Stone article and Michelle McNamara’s book on the Golden State Killer, were located through previous research projects and found to be reliable and factual in nature.
Burnett, C. G. (2010). If only: Best practices for evidence retention in the wake of the DNA revolution. South Texas Law Review, 52(3), 335–358.
Dery, G. M., III. (2019). Can a distant relative allow the government access to your DNA? Hastings Science and Technology Law Journal, 10(2), 103–146.
Deray, E. S. (2011). The double-helix double-edged sword: Comparing DNA retention policies of the United States and the United Kingdom. Vanderbilt Journal of Transnational Law, 44(3), 745–776.
United States v. Pool, 645 F. Supp. 2d 903, 906 (E.D. Cal. 2009).
Maryland v. King, 569 U.S. 435 (2013).
Logan, W. A. (2015). Government retention and use of unlawfully secured DNA evidence. Texas Tech Law Review, 48(1), 269–286.
Hazel, J. W., & Slobogin, C. (2021). “A world of difference”? Law enforcement, genetic data, and the Fourth Amendment. Duke Law Journal, 70(4), 705–774.
Ehrlich, B. (2020, January 14). True crime podcast leads to arrest in 40-year-old cold case. Rolling Stone. rollingstone.com ?
Katz v. United States, 389 U.S. 347 (1967).
United States Department of Justice. (2020, November 19). Department of Justice announces interim policy on emerging method to generate leads for unsolved violent crimes. justice.gov ?
McNamara, M. (2019). I’ll Be Gone in the Dark: One Woman’s Obsessive Search for the Golden State Killer. Harper Perennial.
Kazemian, L., Pease, K., & Farrington, D. P. (2011). DNA retention policies: The potential contribution of criminal career research. European Journal of Criminology, 8(1), 48–64.
Strom, K. J., Hickman, M. J., & Ropero-Miller, J. D. (2011). Evidence retention policies in U.S. law enforcement agencies: Implications for unsolved cases and postconviction DNA testing. Journal of Contemporary Criminal Justice, 27(2), 133–148.
Innocence Project. (2021, April 27). Explore the numbers: Innocence Project’s cases and impact. innocenceproject.org ?
