Book Review: I Know Who You Are, by Barbara Rae-Venter

Book Review

I Know Who You Are: How an Amateur Sleuth Unmasked the Golden State Killer and Changed Crime Fighting Forever

by Barbara Rae-Venter, 2023, Ballantine Books, New York

Do you have even a passing interest in using genetic genealogy for justice?  Do you want to learn how the pros solve cases?  Are you concerned about government agents and for-profit companies rifling through the genomic information of citizens?  Then you should read Barbara Rae-Venter’s book “I Know Who You Are,” because it’s all here.1 

Throughout, Rae-Venter interweaves true-crime horror with investigative details and vignettes from her own life.  The result is an engaging, well-written book that gives valuable insight into the power and practice of forensic genetic genealogy (FGG; sometimes also called investigative genetic genealogy or IGG). 

The book has a glaring weakness, though:  its treatment of the ethical and constitutional issues surrounding FGG.  It presents a classic example of what my colleague Lindsay Carter calls “noble cause bias,” in which righteous ends justify inappropriate means.  


The Cases

The cases themselves are best described by Rae-Venter herself, so I will only touch on the highlights.  Rae-Venter’s first law-enforcement case was that of Lisa Jensen, a woman who had been abducted as a toddler and abandoned a few years later in California.  Lisa wanted to know her true identity, and Rae-Venter volunteered to help adoptees find their biological families as a hobby in retirement.  A collaboration was a good fit.  In working Lisa’s case, Rae-Venter’s team stumbled across a grisly quadruple-murder cold case in New Hampshire.  Despite being from opposite sides the country, Lisa’s case and the Bear Brook murders were inextricably related.  And Rae-Venter solved them both.

Eventually, news that Rae-Venter had identified Lisa’s mother ultimately reached FBI lawyer Steve Kramer and Contra Costa County Detective Paul Holes.  These two California-based law-enforcement personnel were investigating a long-dormant serial rapist and serial murderer dubbed the Golden State Killer.  Although he’d escaped justice for more than 40 years, Rae-Venter was able to identify him as Joseph James DeAngelo in only 2 months using genetic genealogy.  True to the title of the book, her work changed crime fighting forever.

Rae-Venter recounts several more cases in her book, including another serial rapist, two unidentified murder victims, and a Baby Doe (an infant abandoned immediately after birth).  This work stands as testament to the power and promise of FGG.


The Methods

Genealogists will appreciate that Rae-Venter takes time to explain how she solved each of these cases.  It’s fascinating to see how genetic genealogy works, much like a ratchet notching you one cog at a time ever closer to the answer.  The overall process is the same whether you’re trying to identify an unknown parent, a criminal suspect, or a Doe.

You start with a list of people who share DNA with your case and build speculative trees for these so-called “DNA matches.”  The goal is to figure out how some of them are related to one another.  Then, you work your way forward in time from their most recent common ancestor (MRCA) until you find where your case fits in.  This is, of course, an oversimplification, but it’s a reasonable one given that this book is targeted to a lay audience.

A key theme in the book is scientific advance, both in DNA analysis and genealogy methods.    DeAngelo’s genetic profile came from a rape kit that had been stored in a freezer for decades.  The DNA was still in excellent shape, and the lab analysis was fairly straightforward.  The Bear Brook victims, on the other hand, were so badly decayed that even the standard law-enforcement profile, called CODIS, failed.  Genetic genealogy profiles, which are about 35,000 times more detailed than CODIS (≈700,000 DNA data points versus ≈20), seemed hopeless. 

Rae-Venter’s “grasshopper mind” allowed her to extrapolate from a news article about 145-year-old remains unearthed during a home renovation to the potential of analyzing hair shafts of the Bear Brook victims.  That led to a productive collaboration with Professor Ed Green of the University of California, Santa Cruz.  Dr. Green’s lab has since developed methods that have assisted numerous FGG cases by Rae-Venter and others.

In parallel, Rae-Venter highlights advances in genetic genealogy methods.  DNA segment triangulation was cutting edge in 2015 when Rae-Venter began work on the Jensen case, but it has been superseded by more efficient and effective methods like clustering and the What Are the Odds (WATO) tool.  Five years from now, clustering and WATO may well be outdated.  Genetic genealogy is still a rapidly developing science and new methods arise frequently, which is part of what makes it so exciting. 

One aspect of Rae-Venter’s approach with which I disagree is her insistence that every name added to a speculative tree be supported by documentation.  Think of it this way:  a DNA match who is a 3rd cousin has sixteen great-great grandparents.  Only two of them (highlighted in the hypothetical tree below) are relevant to your case.  Initially, you don’t know which two.  

If you were to find documentary records for every one of the match’s ancestors, you’d have to research 30 people when only five are relevant:  one parent, one grandparent, one great grandparent, and the shared great-great grandparent couple.  That’s six times more work than is necessary.  For a fourth cousin, the difference is more than 10-fold (62 ancestors with 6 relevant).  Worse, to identify the MRCA, you’d have to build such trees for several matches until you found the ancestors common to all of them.

A far more efficient approach is to build a “quick and dirty” tree for each match with little to no documentation.  This allows you to quickly identify likely MRCAs.  Then, you double back to corroborate only the relevant lines with documentation.  Rae-Venter argues that “one errant name can set a search back countless days or even months,” but I would argue the opposite; too much attention to irrelevant detail will prolong the search unnecessarily.


Noble Cause Bias

The term “noble cause bias” has its roots in the concept of noble cause corruption, in which someone perceives that their desired end is more important than the law.  To be clear, Rae-Venter’s actions and those of her law-enforcement colleagues were not “corrupt” in the legal sense; at the time, there were no laws about FGG at all, and few exist even now.  However, the field is an ethical and constitutional minefield, and Rae-Venter’s blindness on that front is stunning.  As she writes, “Identifying victims and criminals felt like a good and noble endeavor, and I did not see it as a two-sided issue.”

The first clue that the issue does, indeed, have two sides came early on, when all but one genetic genealogy company refused to analyze the Golden State Killer’s DNA.  Steve Kramer approached all of them, but only FamilyTreeDNA was willing to help.  Rae-Venter writes “I personally did not feel that there were any pressing ethical issues stemming from the use of commercial DNA sites in criminal cases,” even though the majority of the industry obviously disagreed.

The second clue was when then-CEO Bennett Greenspan agreed on the spot to participate but asked that his company’s involvement be hidden from the public.  Oh c’mon.  If exposing his 1.5 million customers to a criminal investigation without their consent was ethically sound, why hide it?  Instead, when the arrest was made, one of the investigative team members threw GEDmatch under the bus, although its owners had no knowledge of the case at the time.

The third clue was the immediate outrage among both genealogists and the broader public when the infiltration of genealogy databases was revealed.  The firestorm may have cost the industry more than a billion dollars (billion with a B).  Consider the graph below.  The dashed lines project how large each database would be today if sales hadn’t taken a huge hit immediately after the Golden State Killer story became public in April 2018.  By my estimates, nearly twice as many people would have done genealogy tests by now had the ethical implications been addressed before FGG was used.

And yet, Rae-Venter doubles down.  “I believe the community actually needs to push for more access from [AncestryDNA and 23andMe], until they give their subscribers the option to help law-enforcement and permit forensic files to be uploaded to their sites.”  Never mind that customers can already help law enforcement by uploading their DNA files to a database that permits that use; they don’t want to.


The Ethics

I’ll save a deep analysis of the ethical concerns surrounding FGG for another post.  For now, ask yourself whether the U.S. government has the right to analyze your genome—and hand that information off to for-profit databases and private contractors—without your knowledge or consent.  Bear in mind that your genome is more than just the “DNA fingerprints” that law enforcement has used for decades; it contains highly personal familial and biomedical information that the Supreme Court itself recognized as posing Fourth Amendment concerns.2

I’m not asking about criminals; I’m asking about you, your children, and all of the other innocent people in your life.  Are you okay with that?  Because that’s what happened to “Teresa” in the book.  

Teresa’s crime?  None.  None whatsoever.  Teresa’s cousin was so traumatized by an unwanted pregnancy that she mentally detached from her own body for 9 months, gave birth in a dirty bathroom in less than 15 minutes, panicked, and walked away.  And that apparently made Teresa’s DNA fair game.  She probably has no idea even now.

Regardless of where you stand on FGG, you should read this book.  It may thrill you.  It may appall you.  It may do both.  But it will definitely get you thinking.


1 This is an affiliate link that will pay a small commission if you purchase the book after clicking on it.  The cost is the same for you, and the income helps to keep this blog free.

2 Maryland v King, p. 27.

24 thoughts on “Book Review: I Know Who You Are, by Barbara Rae-Venter”

  1. I do not understand why there is a moral or ethical dilemma about adding any dna to a dna database, there are thousands of cases in the US never solved and probably never will be because of this.Many States have rape kits that have never been tested due to lack of funds and where are those rapists? Probably still doing it.

    1. Many people, myself included, believe that it’s unethical to use our DNA data for any purpose without our explicit consent.

      1. Yeah, you’ve always been anti GEDmatch and FTDNA. I’m the opposite. So good they are seeking out criminals.

        1. No, not always. I was a big fan of GEDmatch until they violated their own Terms of Service.

  2. When exposure of LE using some of the testings company’s data bases, some of us lost some of our matches at Gedmatch and FTDNA. In particular, I lost a 3-4th cousin and her 3 brothers who disappeared from my match list (that I noticed). Wonder what they had to hide? I had already triangulated with them and copied the information. Glad I did. It was a good TG.

  3. Leah
    I’m going to get this one since you recommended it. You know I’m in the DAR,I think and they’ve just made new “regime” changes which tap my personal interest in my Bio father’s line.
    I am an Admin for 2 FTDNA groups. I just joined the 2 FTDNA Welsh groups. My first cousin who tested at Nat, Geo. 2006. is now 1 marker from our Big Y. I began then to work with it. I have given guidance, besides my own GF to 4-5 unknowns. Guess I’ll give up on LivingD. who seem careless with kits. Also with your OK next week I will present your very important Stats to my own DAR chapter of 17 years. I appreciate your advice. Kathleen

  4. The database tester graph is a great illustration of how GEDmatch is an under-used resource if more testers copied their data. It is not only free for a small number of kits but there is an opt out for law enforcement. Your commentary indicated that GEDmatch was somewhat of an innocent party in the GSK case so I am curious to your source of gengen tools if not using GEDmatch and whether all the changes that have taken place in the intervening years mean you will use it again?
    As a gengen I do get consent from those I work with for sharing their data more widely as otherwise some case would not be solved. Ancestry-hidden data is a big barrier to all.

      1. Your position is obviously clear, but there has been a change of ownership at GEDmatch and the T&Cs under the new regime are more robust. A lot of time has gone by since TGSK. Without GEDmatch I would not be able to access a lot of Ancestry and 23andMe segment data which have been key to solving adoptions and NPEs. They are the 2 largest databases and largely inaccessible unless testers have the finances to test with all which most do not. I would not know anything about my cousins in Iceland, for example, and they would still seeking their origins had I not recognised a family-branch-defining segment on GEDmatch. I find using anonymity on GEDmatch and a dedicated gmail address additional safeguards should anyone try to bypass the T&Cs.

        1. After Verogen bought GEDmatch, they redefined what “law enforcement” means such that everyone is exposed to some criminal cases, regardless of their settings. GEDmatch didn’t tell their users about this. Instead, they sent out an email reassuring that user settings hadn’t changed without telling them that the same settings now meant something different.

  5. Wow, thank you for this well-written book report. You’ve given me a lot to think about when I thought I had already made up my mind. I’m definitely putting this book on my list.

  6. But the analysisof the kits sold, may not be attributal to the law enforcement debacle: Mightn’t also show a plateauing of kits sales due to saturation point, especially in the US? Maybe we’ve reached a point where those who want to take a test, has done so? Let’s fae it you’re never going to get even close to 100% kits sales. Ininite growth just wont happen. My Heritage does’nt seem to be that affected, maybe becuase of increased interest from Europe.

    1. That’s a reasonable question. I don’t think market saturation is the explanation for a few reasons. First, the hit to sales came immediately after GSK was publicized. If market saturation was at play, that’s a pretty big coincidence in timing. Second, Anne Wojcicki herself has said that GSK caused sales to fall; she has access to better market data than you or I do. Anecdotally, I’ve heard the same from Ancestry employees, but not in a format I could cite. Third, both AncestryDNA and 23andMe were impacted at the same time even though they are in different markets (genealogy versus health). Fourth, market saturation causes the curve to get flatter and flatter. That’s not what we’re seeing. Growth across the board is essentially linear, just at a much lower rate than before.

  7. One possible reason Rae-Venter’s methodology is to research all possible ancestors (rather than only the most likely) is to exclude those from being a possible MRCA. Can you imagine answering the question in court “how do you know …… wasn’t the MRCA?” It would be a tactic to discredit her methodology. She needed to be able to respond truthfully to that line of question.

    1. She doesn’t testify in court. In fact, the FBI and other practitioners of FGG are trying very hard to keep the genealogy out of the courtroom. They argue that it’s “just a lead” so doesn’t belong there. I believe that’s why they now favor the term “Investigative Genetic Genealogy” over “Forensic Genetic Genealogy” (which, implies a court of law).

  8. Got the audible version tonight after reading your post and although I’m only to the resolution of Lisa Jensen’s identity I’m wondering what took so long – the smaller size of the databases 5 yrs ago? I’ve solved a bunch of unknown parentage cases using just Ancestry usually within 2-3days.
    It’s a shame that her grandfather almost missed out of knowing her because of his resistance to testing. 😭
    My DNA is everywhere and I’m a total geek too but I worry about the government using evolving knowledge against us. Seems like there was some talk around the same time about Wojcicki partnering with Branson or Gates regarding targeted pharmaceuticals or something… 🤔 And then there’s the whole “was Covid the result of bio weapon tinkering run amok?” talk.
    Whatever may come now, Pandora’s Box is irreversibly wide open.

  9. I’m all for solving crimes,, Jane/John Does, etc. however, I agree they cannot and should not go against the rules already established.

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