Cold Cases Solved by Genetic Genealogy: How DNA Cracks Decades-Old Crimes

Since April 2018, a single forensic breakthrough has done what decades of traditional detective work could not: put names to the nameless and faces to the faceless. Cold cases solved by genetic genealogy now number more than 651 criminal investigations as of December 2023, with 318 individual perpetrators identified and 464 previously unidentified decedents given back their names (Forensic Genetic Genealogy Project, 2023). Families who spent lifetimes waiting for answers are finally getting them. Killers who believed time had erased their crimes are learning otherwise. Investigative genetic genealogy has fundamentally rewritten the rules of cold case investigation, and the pace is accelerating.

This is the story of how it works, the landmark cases that proved its power, and the legal and ethical questions that trail close behind.

What Is Forensic Genetic Genealogy?

Forensic genetic genealogy sits at the intersection of two fields that, until recently, occupied entirely separate worlds: forensic DNA analysis and consumer genealogy research. The discipline combines crime scene DNA evidence with the massive databases built by direct-to-consumer DNA testing companies to identify suspects and victims through their family connections.

Traditional forensic DNA testing relies on a straightforward comparison. Investigators collect a biological sample from a crime scene, develop a DNA profile, and run that profile against law enforcement databases like CODIS (Combined DNA Index System). If the perpetrator’s DNA is already in the system, a match emerges. If it is not, the case stalls.

Forensic genealogy bypasses that limitation entirely. Instead of requiring the suspect’s own DNA to be on file, the process works through relatives. A genetic genealogist extracts a SNP profile (single nucleotide polymorphism profile) from the crime scene sample and uploads it to public genealogy databases such as GEDmatch or FamilyTreeDNA (National Institute of Justice, 2019). These platforms contain the voluntarily submitted DNA data of millions of people who tested their ancestry through companies like 23andMe and AncestryDNA.

The method does not require a direct match. Even a distant cousin DNA match, sometimes a third or fourth cousin sharing less than one percent of their DNA with the unknown individual, provides enough of a thread for a skilled genetic genealogist to pull. From that thread, the investigator reconstructs entire family trees spanning generations, narrowing the pool of possible identities until a single candidate emerges.

How Investigative Genetic Genealogy Works: The Process Step by Step

The investigative genetic genealogy process is methodical, painstaking, and often takes months of work by specialized analysts. Here is how a typical case unfolds.

Step 1: DNA Extraction and Sequencing. The process begins with a viable biological sample from the crime scene: blood, semen, saliva, hair roots, or tissue from unidentified remains. A forensic laboratory extracts DNA and generates a SNP profile containing hundreds of thousands of genetic markers, distinct from the short tandem repeat (STR) profiles used in CODIS (Parabon NanoLabs, 2020).

Step 2: Database Upload and Search. The SNP profile is uploaded to one or more genealogy databases that permit law enforcement searches. GEDmatch and FamilyTreeDNA are the two primary platforms that have explicitly opted into allowing such access (GEDmatch, 2019). The system scans for any user whose DNA shares significant segments with the uploaded profile, flagging potential relatives.

Step 3: Identifying Genetic Matches. The search returns a list of genetic matches ranked by the amount of shared DNA. Close relatives share more DNA; distant cousins share less. In most forensic cases, the closest matches are second, third, or fourth cousins, people who share a set of great-grandparents or great-great-grandparents with the unknown individual (Kling et al., 2021).

Step 4: Building Reverse Family Trees. Starting from each identified genetic match, the genealogist constructs that person’s family tree backward through generations using public records: birth certificates, marriage licenses, census data, obituaries, and immigration records. The goal is to find where the family trees of multiple genetic matches converge on a common ancestor (Parabon NanoLabs, 2020).

Step 5: Narrowing the Candidate List. From the common ancestors, the genealogist works forward through descendants, applying filters based on age, sex, geography, and timeline. A murder committed in Sacramento in 1978 eliminates descendants who were children at the time or who lived on the East Coast.

Step 6: Confirmatory DNA Testing. Once investigators identify a prime suspect, they obtain a fresh DNA sample, often from discarded items like a coffee cup or cigarette butt left in a public place. This sample is tested against the original crime scene evidence using traditional STR analysis. A match confirms the identification.

The entire process can take anywhere from weeks to over a year, depending on the quality of the original DNA sample and the density of genetic matches in the database (National Institute of Justice, 2021).

The Golden State Killer: The Case That Changed Everything

No discussion of cold cases solved by genetic genealogy is complete without the case that launched the entire field into public consciousness.

Between 1974 and 1986, a single predator terrorized California. He committed at least 13 murders, more than 50 sexual assaults, and over 100 burglaries across multiple jurisdictions (FBI, 2018). Investigators gave him different names in different regions: the Visalia Ransacker, the East Area Rapist, the Original Night Stalker. It took decades to confirm these were all the same man.

DNA linked the crime sprees in 2001, but the profile generated no hits in CODIS. The case went cold again.

In 2018, investigator Paul Holes and attorney Anne Marie Schubert enlisted genetic genealogist Barbara Rae-Venter. Working with a crime scene DNA sample, Rae-Venter uploaded a SNP profile to GEDmatch and identified distant relatives of the unknown offender. Through meticulous genealogical research, she traced multiple family lines to Joseph James DeAngelo, a 72-year-old former police officer living in Citrus Heights, California (Holes, 2018).

Investigators collected DNA from a discarded item in DeAngelo’s trash. It matched. On April 24, 2018, DeAngelo was arrested.

In June 2020, DeAngelo pleaded guilty to 13 counts of first-degree murder and 13 counts of kidnapping, receiving multiple consecutive life sentences without parole (Sacramento County District Attorney, 2020).

The arrest did more than close one case. It demonstrated to every law enforcement agency in the country that genetic genealogy could solve the unsolvable. In the months that followed, cold case units nationwide began submitting decades-old DNA evidence for forensic genealogy analysis. For families who endured forty years without answers, the arrest delivered something beyond justice.

Bear Brook Murders: Naming the Nameless

The Bear Brook case stands as one of the most extraordinary demonstrations of what forensic genetic genealogy can accomplish, because it did not just identify a killer. It gave names back to four people who had been stripped of their identities.

In 1985, a hunter discovered a steel barrel in Bear Brook State Park in Allenstown, New Hampshire. Inside were the remains of a woman and a young girl. In 2000, a second barrel was found nearby, containing the remains of two more children (New Hampshire Attorney General, 2019).

For decades, investigators could not determine who these four people were, let alone who killed them. Traditional forensic methods generated no identifications.

In 2017, genetic genealogist Barbara Rae-Venter began working the Bear Brook case. Using DNA from the unidentified remains and familial DNA searching through genealogy databases, she identified the adult woman as Marlyse Elizabeth Honeychurch and two of the children as her daughters, Marie Elizabeth Vaughn and Sarah Lynn McWaters (New Hampshire Attorney General, 2019).

The killer was Terry Rasmussen, a drifter and serial criminal who had died in a California prison in 2010. Rasmussen operated under numerous aliases, and investigators believe he murdered additional victims across multiple states. The genetic genealogy investigation revealed the third child was Rasmussen’s own daughter, a discovery that deepened the horror of an already devastating case.

The Bear Brook murders underscore a dimension of forensic genetic genealogy solved cases that often receives less attention than catching killers: identifying unidentified remains. Across the United States, approximately 40,000 sets of human remains sit in medical examiner offices and forensic labs without names (National Missing and Unidentified Persons System, 2023). Many cases on our site involve this exact anguish. The unsolved disappearance of Linda Sherman, for instance, involved the discovery of a skull years later and the painstaking forensic work required to analyze remains when identification is uncertain.

Genetic genealogy offers these unnamed dead, and their families, a path toward recognition that previously did not exist.

The Boy in the Box: 65 Years to an Answer

On February 25, 1957, the body of a young boy was found inside a cardboard box in the Fox Chase neighborhood of Philadelphia. He was approximately four to six years old. He had been beaten. No one came forward to claim him (Philadelphia Police Department, 2022).

The case became one of the most enduring mysteries in American criminal history. The boy was buried under a headstone that read “America’s Unknown Child.” Investigators pursued thousands of leads over the decades. None led to an identification.

In 2019, the Philadelphia Police Department authorized the use of forensic genetic genealogy. Investigators exhumed the boy’s remains and submitted DNA for SNP analysis. Through genealogy database searches and the construction of extensive family trees, genetic genealogists identified the child as Joseph Augustus Zarelli in December 2022 (Philadelphia Police Department, 2022).

The identification, 65 years after his death, demonstrates the extraordinary reach of genetic genealogy across time. Even when every witness has died, when records have been lost, and when living memory has faded, the biological evidence persists. DNA does not forget.

The investigation into who killed Joseph Augustus Zarelli continues, but his name has been restored. For a boy who spent more than six decades as a symbol of anonymous suffering, that restoration carries profound significance.

Cold Cases Solved by Genetic Genealogy: A Growing List

The Golden State Killer, Bear Brook, and the Boy in the Box represent the highest-profile successes, but they are far from alone. The list of cold cases solved by genetic genealogy grows steadily, and the range of case types is broad.

Cold Case Homicides. Genetic genealogy has resolved murders spanning decades. The 1987 murder of Jay Cook and Tanya Van Cuylenborg in Washington State was solved in 2018 when forensic genealogy identified William Earl Talbott II as the killer (Snohomish County Sheriff’s Office, 2018). The 1992 murder of Christine Jessop in Ontario, Canada, was resolved through genetic genealogy in 2020, identifying Calvin Hoover as the perpetrator (Ontario Provincial Police, 2020).

Sexual Assault Cases. The criminal genetic genealogy database approach has proven effective in identifying serial sexual offenders. The Ramsey Street Rapist, responsible for assaults in Fayetteville, North Carolina, in the 2006 era, was identified as Darold Wayne Bowden through genetic genealogy in 2019 (Fayetteville Police Department, 2019).

Unidentified Remains. Beyond the Bear Brook and Boy in the Box cases, genetic genealogy has returned names to hundreds of unidentified decedents. The “Buckskin Girl,” found murdered in Ohio in 1981, was identified as Marcia Louise King in 2018, one of the earliest identifications using this technology (Miami County Sheriff’s Office, 2018).

Many active investigations across the country may eventually benefit from the same methodology. Cases like the unsolved Delphi murders of Abigail Williams and Liberty German demonstrate how digital evidence and modern forensic tools can converge in complex investigations. Similarly, the unsolved murder of Bonnie Huffman is the kind of cold case homicide where existing forensic evidence such as latent fingerprints could potentially be paired with emerging genetic technologies.

The FBI’s major cases division continues to classify numerous unsolved homicides as active, and genetic genealogy represents one of the most promising avenues for resolution.

The Technology Behind DNA Phenotyping and Genealogy Databases

Two technological pillars support the forensic genealogy revolution: SNP genotyping and DNA phenotyping.

SNP Genotyping forms the backbone of genetic genealogy identification. Single nucleotide polymorphisms are variations at individual positions in the DNA sequence. A standard SNP profile used in forensic genealogy captures between 600,000 and 900,000 individual markers. These markers are the same ones analyzed by direct-to-consumer DNA testing services like 23andMe and AncestryDNA, which is what makes the database comparison possible (Greytak et al., 2019).

The quality of results depends heavily on the quality of the original DNA sample. Degraded or mixed samples produce incomplete SNP profiles that generate fewer and less reliable matches. Advances in DNA extraction techniques continue to improve the success rate with challenging samples (National Institute of Justice, 2021).

DNA Phenotyping is a complementary technology that predicts an individual’s physical appearance from their DNA. Companies like Parabon NanoLabs use proprietary algorithms to generate predictions about eye color, hair color, skin tone, face shape, and ancestry from a DNA sample (Parabon NanoLabs, 2020). While DNA phenotyping cannot provide a photograph-quality likeness, it narrows the physical description of an unknown suspect or victim, which helps investigators prioritize leads when genetic genealogy returns multiple candidates.

Genealogy Databases are the third critical component. GEDmatch, a free and open platform, emerged as the primary database used in forensic genetic genealogy after the Golden State Killer case. Following public debate about privacy, GEDmatch changed its default settings in 2019 to require users to explicitly opt in to law enforcement matching (GEDmatch, 2019). FamilyTreeDNA also permits law enforcement searches with user consent. Major commercial services like AncestryDNA and 23andMe do not allow law enforcement access without a valid legal order (23andMe, 2019).

The effectiveness of the system depends on database size. Current estimates suggest that databases accessible to law enforcement cover enough of the U.S. population of European descent that investigators can find at least a third-cousin match for the majority of individuals in that group (Erlich et al., 2018). Coverage for other ancestry groups remains significantly lower, a disparity that raises equity concerns.

Legal and Ethical Debates Surrounding Genetic Genealogy

The power of forensic genetic genealogy comes with substantial legal and ethical questions that law enforcement agencies, legislators, and civil liberties organizations continue to debate.

Privacy Concerns. The central tension is straightforward: when a person submits their DNA to a genealogy database, they expose not only their own genetic information but also that of every biological relative, including relatives who never consented to any testing. A single DNA submission can implicate family members across multiple generations. Civil liberties organizations, including the ACLU, have raised concerns about the scope of genetic surveillance this enables (ACLU, 2019).

Fourth Amendment Questions. Courts have not reached a definitive consensus on whether law enforcement’s use of public genealogy databases constitutes a search under the Fourth Amendment. In Carpenter v. United States (2018), the Supreme Court expanded protections to certain digital records, but the ruling did not directly address genetic genealogy (Ram, 2018).

The DOJ Interim Policy. In 2019, the U.S. Department of Justice issued an interim policy restricting the technique to violent crimes and unidentified remains cases, requiring that traditional methods be exhausted first, and mandating that uploads occur only on databases with terms of service permitting law enforcement use (U.S. Department of Justice, 2019). Many state and local agencies have adopted similar guidelines.

Genealogy Database Policies. The databases themselves have become key players in the ethical landscape. GEDmatch’s 2019 shift to opt-in for law enforcement matching was a direct response to privacy concerns raised after the Golden State Killer case. The ISOGG Wiki maintains detailed documentation on the evolving policies of various databases and the legal frameworks governing their use.

Racial and Demographic Disparities. Because genetic genealogy databases are disproportionately populated by individuals of European descent, the technology is more effective for cases involving white suspects and victims, raising questions about equitable application of forensic resources (National Institute of Justice, 2021).

Cases like the unresolved disappearance of Asha Degree, where evidence has been analyzed at the FBI laboratory in Quantico, highlight the intersection between advanced forensic capabilities and ongoing investigations where every available technology matters. Similarly, the unsolved disappearance of Brandon Lawson illustrates how modern investigative tools continue to evolve in the search for answers.

How Law Enforcement Agencies Are Adopting This Technology

The adoption of genetic genealogy by law enforcement has moved from experimental to institutional since 2018. Several developments mark the trajectory.

Dedicated Forensic Genealogy Units. A growing number of agencies have created specialized units focused on forensic genealogy. The FBI’s CODIS unit works alongside genealogy specialists, and state-level agencies in California, Texas, Florida, and Virginia have established programs or contracted with private laboratories like Parabon NanoLabs and Othram Inc. (National Institute of Justice, 2021).

Private Sector Partnerships. Companies specializing in forensic genetic genealogy have become essential partners. Parabon NanoLabs pioneered the commercial application of genetic genealogy to criminal cases. Othram Inc. operates a laboratory designed to extract DNA from degraded forensic samples, expanding the range of cases amenable to analysis (Othram, 2022).

Federal Funding and Support. The National Institute of Justice has allocated grant funding for forensic genetic genealogy research and case processing, and the Bureau of Justice Assistance has supported cold case investigations incorporating genealogical methods (National Institute of Justice, 2021).

Training and Certification. The field is developing formal training pathways. Organizations like the Forensic Genealogy Standards Board are working toward certification standards for genetic genealogists who work on criminal cases, aiming to ensure methodological rigor and reduce misidentification risk (Forensic Genealogy Standards Board, 2022).

State Legislation. At least a dozen states have introduced or passed legislation addressing the use of genetic genealogy by law enforcement. Maryland became one of the first to enact comprehensive regulations in 2021, requiring judicial authorization, limiting the technique to certain crime categories, and mandating destruction of genetic data after case resolution (Maryland General Assembly, 2021).

Genetic genealogy is moving from a novel investigative tool to a standard component of the cold case investigation toolkit.

The Future of Genetic Genealogy in Criminal Investigations

Several emerging trends indicate where forensic genetic genealogy is headed in the coming years.

Expanding Database Coverage. As more consumers participate in DNA testing and opt into law enforcement matching, database coverage grows. Researchers project that once genealogy databases contain profiles for approximately two percent of a target population, virtually every individual can be identified through familial connections (Erlich et al., 2018). For populations of European descent in the United States, that threshold is approaching. For other populations, significant gaps remain.

Improved DNA Recovery. Advances in DNA extraction and amplification techniques are making it possible to generate usable SNP profiles from smaller, more degraded, and older biological samples. Cases involving remains that are decades or even centuries old may become amenable to forensic genealogy as laboratory methods improve (Othram, 2022).

International Cooperation. Forensic genetic genealogy is expanding beyond the United States. Agencies in Canada, Australia, the United Kingdom, and several European countries have begun using or evaluating the technique, though differing legal frameworks present challenges for cross-border cases (Wikipedia: Investigative genetic genealogy).

Integration with Other Forensic Technologies. The combination of genetic genealogy with DNA phenotyping, isotope analysis, and digital forensics creates increasingly powerful investigative packages. An unidentified set of remains can potentially yield a physical description, a geographic history, and a name through a single integrated forensic workflow.

Proactive Investigation. Some agencies have begun using genetic genealogy proactively, processing backlogs of unsubmitted sexual assault kits and re-examining cold case evidence previously considered insufficient. This approach has the potential to resolve large numbers of cases that were never actively investigated using modern forensic methods.

The ethical and legal frameworks will need to keep pace with these technical advances. What is already clear is that forensic genetic genealogy has permanently altered the landscape of criminal investigation. Cases once considered permanently cold now carry the possibility of resolution.

For the families of victims, that possibility is everything.

FAQ: Genetic Genealogy and Cold Cases

How many cold cases have been solved by genetic genealogy? As of December 2023, forensic genetic genealogy has contributed to solving more than 651 criminal cases, resulting in the identification of 318 perpetrators and 464 previously unidentified decedents (Forensic Genetic Genealogy Project, 2023). The number continues to grow as more agencies adopt the technology and process backlogged evidence.

What was the first cold case solved by genetic genealogy? The Golden State Killer case is widely recognized as the first major criminal case solved through forensic genetic genealogy. Joseph James DeAngelo was arrested on April 24, 2018, after genetic genealogist Barbara Rae-Venter identified him through DNA matches on GEDmatch (FBI, 2018). Earlier, smaller-scale uses of the technique existed, but the DeAngelo arrest brought the method to national prominence.

How does genetic genealogy work to solve crimes? Investigators extract a SNP profile from crime scene DNA and upload it to public genealogy databases like GEDmatch or FamilyTreeDNA. The system identifies genetic relatives of the unknown individual, even distant cousins. Genetic genealogists then build family trees from these matches, working through generations of public records to narrow down the suspect or victim’s identity. A confirmatory DNA test on the identified individual seals the identification.

Is genetic genealogy legal for law enforcement? Yes, with conditions. The U.S. Department of Justice issued an interim policy in 2019 permitting its use for violent crimes and unidentified remains investigations, provided traditional methods have been exhausted first (U.S. Department of Justice, 2019). Several states have enacted additional legislation regulating its use. The technique must be conducted on databases whose terms of service permit law enforcement access.

What DNA databases do police use for genetic genealogy? Law enforcement primarily uses GEDmatch and FamilyTreeDNA, both of which have policies permitting forensic searches with user consent. Major commercial services like AncestryDNA and 23andMe do not allow law enforcement access to their databases without a valid court order (23andMe, 2019).

How long does it take to solve a cold case with genetic genealogy? Timelines vary significantly depending on the quality of the DNA sample and the density of matches in genealogy databases. Simple cases with strong DNA and close genetic matches can be resolved in weeks. Complex cases involving degraded DNA, few database matches, or difficult genealogical records can take a year or more (National Institute of Justice, 2021).

Can genetic genealogy identify unknown victims? Yes. Identifying unidentified remains is one of the most impactful applications of forensic genetic genealogy. The technique has returned names to hundreds of previously unknown decedents, including the Bear Brook murder victims and Joseph Augustus Zarelli, the Boy in the Box (Philadelphia Police Department, 2022).

What is the difference between genetic genealogy and traditional DNA testing? Traditional forensic DNA testing (STR analysis) compares a crime scene sample directly against profiles in law enforcement databases like CODIS. It requires the suspect’s own DNA to be in the system. Genetic genealogy uses SNP profiles compared against consumer genealogy databases, and it works through relatives rather than requiring a direct match. This allows identification even when the suspect has never been in the criminal justice system.

Sources

• FBI — Combined DNA Index System (CODIS) — Overview of the federal DNA database system
• DOJ — Investigative Genetic Genealogy Policy (2019) — Federal interim policy on forensic genetic genealogy
• GEDmatch — Genetic genealogy database used in the Golden State Killer identification
• FamilyTreeDNA — Law Enforcement Matching — Consumer genealogy platform with law enforcement access
• Sacramento County District Attorney — Golden State Killer Case — People v. Joseph James DeAngelo prosecution records
• Parabon NanoLabs — Snapshot DNA Phenotyping — Forensic genetic genealogy technology provider
• Innocence Project — DNA Exonerations — Database of wrongful convictions overturned through DNA evidence
• DNA Doe Project — Nonprofit using genetic genealogy to identify unidentified remains
• Philadelphia Police Department — “Boy in the Box” Identification (2022) — Joseph Augustus Zarelli identification through genetic genealogy
• New Hampshire Attorney General — Bear Brook Case — Identification of victims and suspect through genetic genealogy