Familial Searching Solves Cold Cases—At What Cost?

A cold case that had stumped investigators for nearly 41 years was solved last month. The 1976 sexual assault and murder of Karen Klass, ex-wife of Righteous Brother’s singer Bill Medley, shocked her Hermosa Beach, CA community and captured the public interest. Failing to make any arrests for decades, detectives were able to use DNA evidence to eliminate suspects in 1999 but were unable to find a database match. In 2011, investigators decided to try a new technique called a familial search and, after a few attempts, successfully identified the perpetrator.


Familial searching (FS) involves taking a DNA profile obtained from a crime scene and comparing it to profiles in CODIS and other databases to identify male relatives. The DNA profile of an immediate family member, such as a sibling, parent or child, can provide a match that generates new leads for law enforcement. Detectives can then collect additional evidence to narrow down that new pool of individuals to a single suspect.

Last May I wrote a blog featuring a Q & A about FS provided by Mr. Rockne Harmon, a respected member of the forensic community and passionate advocate for FS. Supporters, like Harmon, and opponents agree that this method of obtaining matches to DNA evidence has demonstrated scientific precision and successful outcomes, as in the Klass case. However, it is still considered controversial and most states have not implemented specific policies regarding the application of FS to criminal investigations. So why isn’t the use of FS more widespread?


Concerns about individual privacy rights are at the forefront of resistance to adopt FS. In a recent case, investigators used DNA submitted through Ancestry.com to find a familial match for the perpetrator of an unsolved murder in Idaho. A suspect was identified due to the genetic information his father had provided to the private genetics company. Although companies like Ancestry or 23andMe have their own policies regarding releasing genetic information, it is alarming to think that DNA you submit to a private database could be subject to investigation by law enforcement.

Fourth Amendment

In response to privacy concerns, many jurisdictions have reserved familial searching for investigating violent crimes that remain unsolved and create a public safety risk. Despite this discretion, there is some ambiguity regarding whether constitutional rights related to lawful search and seizure are being violated by FS.

It is legal in the United States for DNA to be taken from convicted felons and stored in CODIS where it will be used to identify offenders in future crimes. The courts have ruled that convicted felons lack any reasonable expectation of privacy, however all others maintain Fourth Amendment privacy rights that prohibit involuntary DNA collection.

In an article published by the Maryland State Bar Association, the author argues that “[b]y securing familial DNA, investigators come to possess DNA of people who are not convicted criminals or even suspects—they are merely family members of those who have been convicted or arrested, or even just suspected of having committed a crime. The probable cause standard is not met to justify the collection of this DNA.”

The essential question is whether or not DNA being virtually collected via family member profiles amounts to collecting DNA involuntarily. Some argue this expectation of privacy is already absent for an innocent individual whose twin’s DNA (and by default their own) is already stored in CODIS. Maryland and the District of Columbia (the only jurisdictions in the United States that ban the use of FS) have decided that FS does violate an individual’s constitutional right to privacy.

Effect on Minorities

Civil rights groups continue to raise concerns about the potential for FS to exacerbate the inequality that already plagues the US criminal justice system. African Americans and Hispanics are disproportionately represented in prison populations and therefore make up the majority of profiles in many databases. The National Association of Criminal Defense Lawyers (NACDL) adopted a resolution to oppose the use of FS during criminal investigations in part because of the potential for FS to disparately impact on these minority populations.

All of these concerns are important considerations as more jurisdictions begin to enact policies regarding the use of FS in criminal investigations. What remains clear is that FS is a proven and effective method of generating leads when all other avenues in an investigation have failed. I think Professor Frederick Bieber (who published a significant paper describing FS) said it best when interviewed about the potential authorization of this method by the Canadian Parliament, “The science is not the issue, it’s really a public policy issue.”

Is familial searching a violation of individual privacy rights? What, if any, limits should be placed on the use of familial searching? Let us know what you think.

Post updated April 11, 2024 to address broken link.

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Darcia Schweitzer
Darcia is a Content Lead at Promega. She earned her BS in Secondary Education at the University of Wisconsin Oshkosh, with minors in Biology and Spanish, and her MS in Biotechnology at the University of Wisconsin Madison. She is passionate about sharing scientific knowledge with all audiences, including her family and friends—whether they have solicited the lesson or not! In her free time, Darcia enjoys reading, playing volleyball, eating delicious food and cheering for the Chicago Cubs.


  1. Thank you for pointing out the privacy issues, and more importantly, the disproportionate impact on communities of color. With so many points of discretion in the criminal justice system, the very real biases and institutional racism mean that we have to be intentional about policy design to make sure the system is actually delivering justice. As scientists, we have a moral responsibility to consider the possible ethical implications throughout the technology development process.

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