How Family Genotyping is Solving Murders (and Raising Ethical Questions)

By Jan Canty, PhD
| June 27, 2025

In recent years, a quiet revolution in crime-solving has been unfolding—not in police labs or courtrooms, but in the world of consumer genetics. The same DNA test kits that people use to explore their ancestry or find long-lost relatives are now helping law enforcement close cold cases and bring long-awaited justice to families of murder victims.

And I wish to be clear on this point. This is NOT a common practice. As of 2024, Ancestry complied with only two valid search warrants. While no central agency tracks this information, people in the field estimate the number of times genetic information was shared for legal reasons to be between 500 – 1000 since 2018. For perspective, that’s roughly 0.001% – 0.0025% of customers whose DNA was used by law enforcement (some of which was obtained voluntarily without a warrant). We have a better chance of being hit by lightning, being drafted by a pro athletic team or earning a perfect SAT score.

And while this tool is a powerful development—it is not without controversy.

From Family Trees to Felonies: The Basics

Services like Ancestry.com and 23andMe experienced a growth surge between 2012 – 2017 when prices dropped dramatically. This made kits more accessible and consumers curiosity about their heritage, health risks, and distant relatives was widespread. But what many people didn’t foresee is that their genetic information—when uploaded to public genealogy databases—could become a tool for solving violent crimes.

Here’s how it works:

A DNA sample is collected at a crime scene (from blood, hair, skin, etc.).
If there’s no match in criminal databases like CODIS (Combined DNA Index System), investigators can upload the DNA profile to third-party public databases like GEDmatch or FamilyTree DNA if they have a warrant to do so.
If a relative of the suspect has used one of these services and consented to public sharing, law enforcement may find a partial match.
Genetic genealogists then build out family trees using publicly available information (census records, obituaries, social media, etc.) to narrow down potential suspects.
Once a likely individual is identified, police obtain a direct DNA sample to confirm the match.

A Case in Point: The 1987 Murder of Carla Walker

Carla Walker was an exuberant, outgoing 17-year-old high school student in Fort Worth, Texas. Sadly, she was abducted from her boyfriend’s car after a Valentine’s Day dance in 1974. Her body was found days later. The case stalled and then went cold for over four decades.

In 2019, a sample from the crime scene was run through forensic genetic genealogy. The result was a match to a family tree that included Glen Samuel McCurley, who had lived near the crime scene at the time. Investigators surveilled McCurley and retrieved DNA from a discarded soda can. It was a match. He was arrested, confessed, and ultimately pled guilty in 2021.

For Carla’s family, it answered a vital question they had wrestled with for many years, “Who killed our Carla?” Someone was finally held accountable.

The Upside: Justice, Answers, and Prevention

Cold case breakthroughs: Victims’ families finally get answers—and justice—after years of silence.
Deterrence: The more cases that are solved this way, the greater the deterrent effect could develop on would-be offenders.
Exonerations: In some cases, genetic genealogy has helped exonerate innocent people who were wrongly accused or convicted.
Cost-effective: Compared to traditional investigations, forensic genealogy can be faster and cheaper once a DNA sample is available.

The Downside: Privacy, Consent, Accuracy

As promising as it sounds, this new frontier raises difficult questions:

Privacy

Many people upload their DNA to find ancestors, not to help solve crimes. Even if you’ve never submitted your DNA, your relatives might have—effectively making you “searchable.” Critics argue this circumvents Fourth Amendment protections against unreasonable searches. And just this year 23AndMe filed for Chapter 11 bankruptcy and offered its assets- including the genetic data of 15 million customers – for sale. This occurred without the consent of consumers, which is why it is currently being challenged legally.

Consent

Only a fraction of users explicitly consent to law enforcement use, but that doesn’t always prevent their data from being used. In the early days, GEDmatch changed its policies after criticism—now users must opt in for law enforcement matching. But not every platform is as transparent. Not opting in gives you more privacy protections, but not absolute immunity from law enforcement access. That’s because a valid warrant can still grant access depending on the company’s compliance policies and legal obligations.

Accuracy and Assumptions

Genetic genealogy doesn’t prove guilt; it narrows the field. Critics warn of potential misidentification if police lean too heavily on suggestive but circumstantial data.

Socioeconomic Disparities

Genetic genealogy relies on voluntary databases from customers who can afford the service. Depending on the type and complexity, a DNA test price may vary between $99 to more than $2000. There are often subscription costs and optional extras such as health reports and family tree building tools. This is an expense that is out of reach for some families, leaving poorer people unrepresented in the genetic database.

In some cases, additional testing may be required, increasing the cost.

A Tool, Not a Silver Bullet

Family genotyping is transforming forensic science in real time. It can be a powerful, life-changing resource for survivors, families, and justice systems. But it must be used with caution, transparency, and public oversight.

As CeCe Moore, a pioneer in investigative genetic genealogy, puts it:

“Every time we solve a case, we’re not just finding a suspect—we’re giving someone their name back, giving a family closure, and making communities safer. But we also have to constantly check ourselves: Just because we can do something, doesn’t always mean we should.”

For now, it’s clear that the double helix doesn’t just tell us where we came from. It may also tell us who’s responsible—and finally bring long-awaited answers to the families who need it most.