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The Golden State Killer Was No Match for Modern Forensics

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Nolan Flynn

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DNA is a powerful tool. We, as humans, leave traces of our presence in the form of imprints and surface contact that analytical forensic scientists can analyze to track us down. Experts can even use these DNA imprints to match them with ancestral DNA to further identify potential suspects. Well, that is exactly what Barbara Rae-Venter did when she collaborated with law enforcement and helped identify the Golden State Killer after police had been searching for over 40 years (O’Toole 2018). And the best part? Rae-Venter made this discovery from the comfort of her own computer.

The Golden State Killer, Joseph James DeAngelo Jr., is an American serial killer and rapist who pleaded guilty in 2018 to his numerous murders and sexual assaults committed between 1974 and 1986 (John 2020). Barbara Rae-Venter described him as a nightmare come to life (Rae-Venter 2024). Over time, the case became more personal for her as she read more about his crimes. In late 2017, she began investigating the ongoing case with some help from law enforcement. However, as a regular civilian, her resources were limited. She was able to access ancestry sites such as MyHeritage and GEDmatch and identify potential relatives based on the DNA found at crime scenes. 

Independently, Rae-Venter uploaded a forensic DNA profile the FBI had developed from DNA found at a crime scene to MyHeritage and GEDmatch. Specifically, single nucleotide polymorphisms (SNPs) were digitally analyzed to identify distant relatives (Rae-Venter 2024). SNPs are specific variations within a single nucleotide of DNA (Wickenheiser 2019). Barbara Rae-Venter used these variations to identify distant genetic relatives of the Golden State Killer, allowing her to reconstruct family trees and help investigators narrow down potential suspects.  

Figure 1: An SNP comparison between DNA strands of two individuals, showing a combination of nucleotide variants along the same chromosome. The blue nucleotides represent matching stretches of SNP alleles between individuals. The orange bracket below the DNA strands indicates the region being compared. A successful SNP comparison should identify meaningful patterns of shared genetic variation. Extended regions of matching nucleotides may suggest shared ancestry. This conceptually illustrates Barbara Rae-Venter’s investigative genetic genealogy as it relates to SNP matching (Ball et al. 2016).

Rae-Venter stumbled upon close matches to distant cousins of DeAngelo by analyzing that the DNA profile had a considerable number of nucleotide matches to other DNA profiles that were already uploaded on ancestry sites (Edge and Coop 2019). From there, Rae-Venter constructed extensive family trees using historical records and birth certificates, creating a major step forward in identifying the prime suspect (Rae-Venter 2024). Eventually, after narrowing down the suspects, the FBI was able to identify DeAngelo as the culprit, as he was the only suspect remaining who fit the profile, leading to his arrest. Finally, after 42 years of relentless investigations, DeAngelo is now serving a total of 26 life sentences thanks to Rae-Venter’s efforts.

Barbara Rae-Venter’s work with computational forensics and genealogy is a prime example of how modern forensics has become an extraordinary tool for criminal justice. Her methods of analyzing SNPs provided law enforcement a major step forward toward identifying one of the most brutal and savage criminals in the United States. She utilizes human traces and imprints by identifying DNA profiles with nucleotide matches to construct a map of DeAngelo’s ancestry, cornering him and making him spend the rest of his life in a jail cell. Moreover, the fact that Rae-Venter is just a civilian with a background in biology who decided to look into this case and managed to solve it speaks volumes about the power of DNA analysis and how digital DNA profiles can be used as a tracker for wanted criminals.

Bibliography

A. Ball, Catherine, J. Barber, Mathew, Byrnes, Jake, et al. 2016. AncestryDNA Matching White Paper. March 31. https://crain-platform-genomeweb-prod.s3.amazonaws.com/s3fs-public/files_copied/ancestrydna-matching-white-paper.pdf

Edge, Michael, and Graham Coop. 2019. “How Lucky Was the Genetic Investigation in the Golden State Killer Case?” Preprint, bioRxiv, January 29. https://doi.org/10.1101/531384.

Kling, Daniel, Christopher Phillips, Debbie Kennett, and Andreas Tillmar. 2021. “Investigative Genetic Genealogy: Current Methods, Knowledge and Practice.” Forensic Science International. Genetics 52 (May): 102474. https://doi.org/10.1016/j.fsigen.2021.102474.

O’Toole, Mary Ellen. 2018. “Understanding Serial Predatory Behavior Through the Lens of the Golden State Killer.” Violence and Gender 5 (2): 65–66. https://doi.org/10.1089/vio.2018.29016.meo.

Rae-Venter, Barbara. 2024. I Know Who You Are: How an Amateur DNA Sleuth Unmasked the Golden State Killer and Changed Crime Fighting Forever. Random House Publishing Group. https://books.google.ca/books?id=OX3cEAAAQBAJ&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q=SNP&f=false

St. John, Paige. 2020. “The Untold Story of How the Golden State Killer Was Found: A Covert Operation and Private DNA.” Los Angeles Times, December 8. https://www.latimes.com/california/story/2020-12-08/man-in-the-window.

Wickenheiser, Ray A. 2019. “Forensic Genealogy, Bioethics and the Golden State Killer Case.” Forensic Science International: Synergy 1 (January): 114–25. https://doi.org/10.1016/j.fsisyn.2019.07.003.

Comments

4 Responses to “The Golden State Killer Was No Match for Modern Forensics”

  1. Nolan Flynn Avatar
    Nolan Flynn

    Hi, iSci. I wrote a forensics-focused blog post because, over time, I have developed a strong interest in forensic science. I recently began researching, in my own free time, how I can use my computer, some coding software, and publicly available information about some active murder cases to see if I can potentially solve or get a clue about the culprits. While seeing if this was actually possible, I stumbled upon the work of Barbara Rae-Venter, a retired attorney with a Ph.D. in biology who apparently was able to solve the case of the Golden State Killer with the resources available at home.

    It’s the fact that she didn’t even work in law enforcement and just assisted them in solving this case because she had a background in biology that really WOWed me, and honestly, I might try this one day when I’m not busy with WineSci and climate change.

    Thanks for checking this out!

    – Nolan

  2. Kristen Taylor Avatar
    Kristen Taylor

    Hi Nolan,

    Fascinating topic choice! It’s impressive how much Barbara Rae-Venter was able to learn about the Golden State Killer using such limited resources! Here are a few suggestions I had for your edits:

    – When you first introduce Rae-Venter in paragraph 2, I recommend adding a very brief description of who she is.

    – I would rephrase the last two sentences of paragraph 2 so that sentence 5 starts with “As a regular…” and sentence 6 with “However, she was…”

    – Make sure to reference your figure somewhere in your text.

    – In your concluding sentence, I suggest adding a comma after the words “solve it” to improve flow.

    Overall, great post and good luck with your edits!
    – Kristen

  3. Isabella Bartlett Avatar
    Isabella Bartlett

    Hey Nolan, great blog post. I really liked your topic choice. I just have a few editing suggestions as follows:

    – This may just be my confusion, but how did Barbara Rae-Venter get a copy of the killer’s DNA to be able to run it through the sites? Perhaps clarify her relation to the case or state if this was public knowledge.

    – Don’t forget to reference your figure in-text to help readers use the visual at the right time. I would suggest P3S3 or P3S4.

    – Your references should be unlinked in the bibliography, as this is what Sarah has shared.

    Overall, great post; I enjoyed learning more about how DNA analysis started to have a place in forensics.

    – Izzy

  4. Heer Upadhyay Avatar
    Heer Upadhyay

    Hi Nolan,

    Wow, I love the topic of your blog post and how you brought in the fields of forensics and DNA analysis! I really enjoyed how it almost felt like reading along the story while connecting to the genetics behind it!

    I have one suggestion: perhaps you could include a sentence or two explaining how exactly SNPs can be used to trace down specific relatives. E.g. are there specific SNPs which match up to certain regions? How unique are they that they can be used to find such extensive family trees, are there multiple SNPs used? I think just a little more scientific detail there would help the content of your post.

    Overall awesome blog post and happy editing!
    Heer

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