How Genetic Genealogy has Cracked Cold Cases: Information for Writers and Other Curious Folks

The information for this article is presented from the research that J. J. Cagney did for her novel. 

J. J. Cagney is a USA Today Bestselling author and named to Kirkus Reviews' 100 Best Books of 2018. Her novel is included in:

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DNA Traces, Investigations, and Websites: How Genetic Genealogy has Cracked Cold Cases

By J. J. Cagney





Cold cases.



Just saying that phrase gives me the shivers because it means a victim’s family and friends never received the why to the crime. I wrote about what that would be like in my novel, Facing the Past.



I found the idea of not knowing why…well, let’s just say I find that upsetting. That’s why I find the study of DNA and its use in law enforcement via GEDmatch (a database that uses DNA profiles) fascinating.



Let’s step back for a moment and talk DNA. We leave at least traces of the stuff wherever we go. Think a hair at the gym, or skin flakes and fingerprints on items we touch in our workplace. Even sipping from a soda can or our to-go coffee leaves behind DNA.



These bits of us are out there, everywhere we go, including at crime scenes. And now, thanks to the explosion of hoe DNA test kits, we have developed a tool that’s helping us not only catch violent criminals but identify unknown victims.


The breakthrough case for DNA genealogical research was the Golden State Killer. Another cold case, called the Buckskin Girl, gave an identity to a “Jane Doe” killed in 1981. Her name is Marcia Lenore Sossoman King, and after nearly 40 years, her family knows what happened to her. I can’t imagine the pain of finding out my child was murdered, but I can understand the need for closure, and that was only possible through studying and matching the victim’s DNA.



The idea to use DNA to solve cases is not new. Years ago, sometime in the 1990s, the FBI set up a national DNA database called CODIS, which is an acronym for the Combined DNA Index System. Problem with CODIS was and is it only calculates about 20 different locations within the human genome. GEDmatch, by contrast, has over 600 million that are specified in the tests provided by 23andMe, which has vastly expanded DNA searches by police personnel. That’s why more and more supposed cold cases are being solved. We finally have the tools to help us place the perpetrators at the crime, thanks to GEDmatch.





What is GEDmatch?


It is a database built by two retirees who wanted more information in their genealogy. The site accepts raw DNA from 23andMe or Ancestry where people can check it against others’ in the database. Originally, this “genetic genealogy” grew out of people’s desires to know more about their family history. But, over time, law enforcement realized the potential. There are thousands of rape kits sitting in labs across the country, the victims’ abuser walking free, because their DNA is not in the FBI’s CODIS. Same goes for murders and other violent crimes. GEDmatch gave the FBI and police forces thousands upon thousands more potential matches, and those personnel are using the data.



“My initial reaction was I was upset,” says Curtis Rogers, co-founder of GEDmatch with John Olson, says when he found out law enforcement agencies were using his site to locate felons. “I didn’t like this use of our website.”



Then came the Golden State Killer arrest. That was a gamechanger because the series of brutal rapes and slayings across California haunted the state’s residents. Rogers and his partner saw the benefit to law enforcement, which outweighed their privacy concerns. So, today, the website notes that any DNA uploaded to the site can and may well be used in a criminal investigation.





How does GEDmatch work?


Each of us is made up of 46 chromosomes, 23 pairs, which we inherit from our parents, who inherited their chromosomes (which we also call DNA) from their parents, etc., etc., back as far as families go. What’s most important to note is the combination from your father and mother may not be an even 50/50 split (i.e., Chromosome 12 might be more closely related to your paternal grandmother than Chromosome 19, which leans toward your maternal grandfather). This makes us each unique, but also helps to identify families.


Another important detail is that these chromosome matches only work back about five or six generations, maybe seven. But, after that, there’s so little of your ancestor left, the tests cannot confirm relationships with as much consistency.


Point being DNA research has its limitations. But it is a powerful tool that we’re just learning how to harness. Last week, GEDmatch’s DNA database helped police solve the cold case of two Alabama teens who were raped and murdered. And DNA samples uploaded to GEDmatch helped solve Sophie Sergie’s brutal murder that occurred in 1993.


It’s a start.



Victims are finally being served justice.



“This is such an obvious way to solve a crime when you have a string of rapes or murders,” Greg Hampikian, director of the Idaho Innocence Project, told Gizmodo. “You have to try.”



Hopefully, law enforcement can continue to solve these cold cases, to give families the closure they deserve.

We appreciate J.J. Gagney for sharing this information - and a new way to twiat your plot.

I'd love for you to support J. J. Cagney and the other twelve authors in the Dead & Gone Serial Killer Boxed Set (including my novel RELIC). A portion of each sale goes to provide funds for the Acacia no-kill shelter.

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