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Barbara Rae-Venter unmasked the Golden State Killer, who eluded capture for over 44 years, using investigative genetic genealogy (IGG).

by Claudia Lascar on 2024-03-20T13:54:00-04:00 in Biology | 0 Comments

Barbara Rae-Venter unmasked the Golden State Killer, who eluded capture for over 44 years, using investigative genetic genealogy (IGG).

Barbara Rae-Venter authored the book: “I Know Who You Are: How an Amateur DNA Sleuth Unmasked the Golden State Killer and Changed Crime Fighting Forever.” This is a fascinating book about science and the importance of forensic DNA testing as a consequential force in shaping the criminal justice system (Rae-Venter, 2023). The author introduces readers to several other complex cold cases to which she contributed before helping solve the notorious Golden State Killer (GSK) case in 2017-8.

Barbara Rae-Venter’s background consists of a Ph.D. in biology, and a degree in law. As a patent lawyer, she specialized in biotechnology inventions related to molecular biology. Since her retirement, Rae-Venter was volunteering for an organization that helped adoptees find their birth relatives, before she was asked by law enforcement to help solve crimes.  She understands the science of DNA and the ins and outs of ancestral research. The IGG is based on a breakthrough Methodology which consists of DNA segment triangulation, which I will briefly describe below using Rae-Venter ‘words:

“If the DNA of Person A (of unknown parentage) matches the DNA of Person B and C at a second-cousin level, and if Person B and C are also second cousins and share a set of grand-grandparents, we can be sure that person A is also a descendant of this set of grand-grandparents (Chapter 2, pg. 16).” The Methodology is quite complex and requires the “building down a descendant line: moving chronologically forward in time through more and more recent generations, starting with the most recent common ancestor (MRCA) of Person B and C – the set of great-grandparents (Chapter 2, pg. 17).  For those with biology knowledge, please note that this Methodology it is unlike the phylogenetic tree.

The GSK terrorized California for twelve years from 1974 to 1986, starting by committing home burglaries and one murder in the San Joaquin Valley, before committing more than fifty rapes (his youngest victims were thirteen), eleven killings, and many other crimes around Sacramento and Los Angeles.  He operated without remorse, but with careful planning by stalking his victims through drainage ditches, or waiting for them in their own home.   “Again and again, the police affidavit mentions homes that back onto drainage channels, or back onto river levees, suggesting that the killer may have used the terrain to remain invisible — until he was ready for his victims to see him” (Selk, 2018). The GSK was the most prolific serial killer ever, but in spite of leaving plenty of DNA and other evidence the law enforcement did not have a clue about him

Paul Holes was the retired former cold-case investigator for the Contra Costa County Sheriff's Office, who for the last twenty-three years worked on his DNA analysis after he acquired a Bachelor of Science in biochemistry. Paul Holes was the one who asked Rae Venter’s help with the case, but he was not able to share with her, a civilian, any of his known information, like for example the criminal Snapshot profile, nor provide her with a DNA sample (Chapter 11, pg. 90.). She was given nothing to work with since she was considered a civilian by the Orange County Sheriff Office, although the GSK left a wealth of DNA evidence behind him in the form of cells, skin, hair, semen at the many crimes’ scenes. With each new advance in DNA technology this evidence was consumed in the hope of acquiring new leads (Chapter 11, pg. 91).

I found the story of how Ray-Venter got access to a pristine sample of DNA captivating, since she refers to this lucky moment when the impossible becomes possible as her “guardian angel” (Chapter 11, pg. 92). In 1980 Charlene Smith, who has been raped multiple times, and both she and her husband Lyman Smith have been killed in their house by the GSK. The Ventura Country assistant medical examiner Dr. Peter Speth arrived at the crime scene to take samples contrary to the preferred method at that time of taking samples at the crime lab. He did not want to contaminate the samples, by bringing the corpses to the crime lab first. Moreover, he insisted on taking not one but two sexual assault kits from the victim Charlene Smith (Chapter 11, pg. 94). He probably was unique in his collection methods. One sample survived for thirty-seven years and was the one that has been used by Ray-Venter to identify the serial killer (Chapter 11, pg. 95).

Family/TreeDNA lab extracted the DNA from the semen in the rape kit and created a SNPs profile (chapter 12, pg. 98.). Single nucleotide polymorphisms, frequently called SNPs (pronounced “snips”), are the most common type of genetic variation among people. The big break came when Ray-Venter uploaded the SNPs profile to the MyHeritage, a relatively new direct-to-consumer genealogic database, which accepted profiles produced by other sites (Chapter 13, pg. 111-2). This allowed her to employ the Methodology(Chapter 13, pg. 112). The GSK turned out to be seventy-two years old Joseph James DeAngelo Jr. a former dishonest cop.

A Sacramento Judge sentenced DeAngelo to multiple life sentences, after he pleated guilty to 76 crimes. This put an end to one of the nation’s most prolific and infamous serial predators.

We have to recognize the important work done by Ray-Venter in this case although she has contributed to many more cases before and after. First and foremost, she was not given any kind of support since she was a civilian. Although Paul Holes worked for more than 23 years, his profile and conclusions were very far from those reached by Ray-Venter in only four months (you need to read the book). This can only be explained by the fact that Ray-Venter is a scientist at heart, and driven by only the knowledge provided by science. There is no exception. Her conclusions are always verifiable. Journal Nature has chosen Barbara Ray-Venter among the most important ten people who mattered in 2018 (Nature, pg. 333, 2018).




“Nature's 10: ten people who mattered this year." Nature 564. (20/27 December 2018): 326-334.


Rae-Venter, B. (2023). I Know who You are: How an Amateur DNA Sleuth Unmasked the Golden State Killer and Changed Crime Fighting Forever. Ballantine Books.


Selk, A. (2018). The most disturbing parts of the 171-page warrant for the Golden State Killer suspect. The Washington Post, 2.

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