Sawtooth Slayer Method

Having read the book “The Sawtooth Slayer” by Nathan Goodwin, I decided to outline the basic methods used to figure out who was the killer. I really enjoyed the book and don’t’ intend to release any spoilers. But I figure the methodology can be useful for those of us searching for our own puzzle.

In Dec 16, 2012 we posted a search method provided by CeCe Moore which you can see here:

How to catch a killer OR learn more about your ancestry!

I want to compare the methods. I’m guessing that they aren’t all that different, perhaps only terminology differences will appear. The effort might teach me more about the overall procedures. You can work with me, and for sure, email me when I make mistakes. Perhaps we can go over the steps at the next DNA Discussions Group via Zoom.

1. DNA test

In this book, the first thing to do is to have a genetic DNA completed and get it to Family Tree DNA and Gedmatch. The following clustering steps can be done most anywhere, but the book is working with police and FamilyTreeDNA and Gedmatch are the only sites that will allow police involvement.

2. Identify clusters containing unique and in-common-with matches

The clusters are built, manually in the book. You can use auto-clustering at MyHeritage or Genetic Affairs if you wish. Clusters are subsets of the matches that contain unique matches that are in common with each other. Given subset uniqueness, each cluster should have a Common Ancestor (CA) and it is our job to find that person or pair. The book ended up with 7 clusters. Given that there are eight 2x great grandparent sets, that is about right. You start with the highest centimorgan match, select in-common-with, going no further than 10 centimorgans. Call that cluster 1. Go to the next not selected match and build cluster 2.

3. Build a speculative family tree of each person within each cluster, looking for the Common Ancestor

This is where the heavy work is involved. Build the trees at I’m seeing one tree per cluster with floating trees inside per person, because after the CA is located, all the “floats” would disappear. You are building the tree backward in time, going towards ancestors. In the book, they built the trees out to 3x great grandparents. I’m not sure why, that might be difficult in some cases.

4. Triangulate within each cluster, this then “closes” each cluster

I know what triangulate means, common segments for 3 or more people. I guess this step is just to prove that the tree building was legitimate, DNA wise. It will sure provide good documentation. Curiously, the first book in the series didn’t need this to close a cluster.

5. Reverse genealogy (p.230)

Reverse genealogy is where all known descendants of the confirmed common ancestors to the genetic network are traced, searching for the overlap between clusters. This is heavier tree building, building forward in time, sometimes using your “find living people” skills. Following the overlap between clusters should lead directly to the original DNA tester.

6. Success. Contact and adapt!

Nathan Dylan Goodwin reviews Barbara Rae-Venter’s New Book

“I have just finished reading an advance copy of Barbara Rae-Venter’s book, I Know Who You Are. As many of you know, she was leading the investigative genetic genealogy aspects of the small team who identified the Golden State Killer. Barbara has been a great help to me with the writing of The Chester Creek Murders and The Sawtooth Slayer, so I was delighted to receive a preview copy of her book. The full review is available on Goodreads by clicking here. I can thoroughly recommend it for anyone interested in the field of investigative genetic genealogy. The book will be released 7th February 2023 and can be pre-ordered here.” (at

The above review came from Nathan Dylan Goodwin’s latest newsletter.

BTW, the company Firebird Forensics Group is owned by genealogist Dr. Barbara Rae-Venter.

Passionate Advocates

Areas that lose their local genealogical societies begin to lose their treasures. We need passionate advocates to join our team.

The Monterey County Genealogical Society (MoCoGenSo) was established to provide education, fellowship, and support to its members and to the community of family history researchers both locally and throughout the world. There are many opportunities for members to participate and help us meet this goal.

Participation can be at one of several levels

  • Board of Directors
  • Officers
  • Volunteers

There are currently openings at each level.

Board of Directors


  1. Attend Board meetings
  2. Represent membership at Board meetings
  3. Vote during Board meetings



  1. Give procedural advice to the Presiding officer and to any member


  1. Be responsible for all incoming and outgoing publications of the Society with the exception of the newsletter
  2. Publish all materials except the newsletter
  3. Be responsible for publication sales
  4. Recommend the purchase of items identified by the local genealogy library and members and act as liaison between libraries and the Society
  5. Present an Annual Summary Report for the Annual Business Meeting


  1. Be responsible for all publicity on behalf of the Society, including advertising for special projects such as fund-raising activities, Society seminar, etc., and work with officers and committee chairpersons
  2. Be in charge of Society displays
  3. Appoint assistants as necessary to perform the duties of office
  4. Present an Annual Summary Report for the Annual Business Meeting
  5. Send or cause to be sent proper notices of all meetings
  6. Notify officers, committees, delegates, and the general membership of any special meeting as necessary

Primary Facebook Administrator

  1. Respond to questions in our Facebook group
  2. Pull in interesting post that relate to genealogy


Volunteers to serve on committees and generally just to help are always welcome. The more help we have, the more we can get accomplished!

The Board of Directors and Officers meets via ZOOM on the 3rd Monday of the month at 7:00 pm.

As you can see, there are opportunities available. Changes occur frequently. Participation can be very rewarding. If one of these opportunities sounds inviting to you, please contact us

” Do what you can, with what you have, where you are.” – Theodore Roosevelt

The Book – A Sawtooth Slayer

Well, the rains came right on time, giving me an excuse to keep reading this newest book by Nathan Dylan Goodwin, The Sawtooth Slayer.  I couldn’t stop until I had read it all. 

The book lays out how modern DNA analysis and genealogy can work together to solve not only cold cases, but current ones as well.  This is the first mystery book that I’ve actually marked up with stickers to help me keep track of the many research sites used during the story.

Nathan is actually a historical, genealogical mystery crime writer, but in this series of books, genetics has been introduced to help solve living crimes.  If you like mysteries, or genealogy you should enjoy this read.

We should get together and trace the clustering methods used and then map out the family trees developed in the story, both forward and “reverse” so we could learn how the conclusions were reached.  And someone should make and share a list of all the research sites mentioned.

A Book – The Sawtooth Slayer

Nathan Dylan Goodwin writes mysteries where investigative genetic genealogy is used to help solve the cases. The books of his that I have previously read have been excellent. This book looks to be the same. I have just started it, but am already finding it hard to put down.

This is a quote from someone who has already read it through.

“I just finished the recent Venator Cold Case book by Nathan Dylan Goodwin….. called The Sawtooth Slayer. I couldn’t put it down. I appreciated the forensic process…. laid out so well by Goodwin… clusters, genetic communities, reverse genealogy. It is all there.”

(The little guy peaking over the top is from my bookmark.)

Family History Centers are now officially named FamilySearch Centers

The name change for centers is official!

In addition to the flagship family research and discovery facility in Salt Lake City, FamilySearch has more than 5,000 local centers where visitors can receive free individualized help and utilize computers to access resources.

The local Monterey California FamilySearch Center is located at 1024 Noche Buena Street in Seaside, CA

Find out more at



Please bear with us as we change the name around this web site. Moving from FHC to FSC is going to take a while.

MoCoGenSo DNA Sig will meet again

The MoCoGenSo DNA Sig will resume operations, with scheduling like before: First Wednesday of the month at noon via Zoom. Reserve the time in your calendar! Due to scheduling difficulties, the restart of our DNA special interest group, originally scheduled for January, has been delayed until February.

Quoting Kathy Nielsen, “Please let us know if you would like to present or share the story of one of the families you have been researching. Or maybe you have a topic or a speaker that you think others might be interested in. Perhaps you can facilitate that meeting. We all learn from each other. “.

What are the benefits of a DNA special interest group?

A DNA special interest group (SIG) is a group of individuals who have a shared interest in using DNA testing for genealogy and family history research. DNA SIGs typically provide a forum for members to share information, resources, and expertise related to DNA testing and genealogy.

Some potential benefits of joining a DNA SIG may include:

  1. Access to information and resources: DNA SIGs often have a wealth of information and resources related to DNA testing and genealogy, including educational materials, case studies, and links to relevant websites and databases.
  2. Opportunities for networking and collaboration: DNA SIGs provide a platform for members to connect with others who have similar interests and to collaborate on research projects.
  3. Expertise and support: DNA SIGs often have members with a wide range of expertise and experience in DNA testing and genealogy. These individuals can provide support and guidance to other members who are new to the field or who have specific questions or challenges.
  4. Community involvement: DNA SIGs can be a great way to get involved in the genealogy community and to contribute to the advancement of DNA testing and genealogy research.

In the meanwhile, there are many great other DNA Sigs and Discussion groups throughout the country that are free for the joining. We have a few right here on the West coast. For example, have you heard of Randy Seaver? He is a long time genealogist who runs a DNA Sig for the Chula Vista Genealogical Society. This link goes to their main page where there is link to the next DNA meeting! Their meetings are via Zoom and are quite interesting. The last one I attended had 32 folks present!

For those who want pure genealogy, Randy Seaver runs a blog that is worth checking out.

And do not forget the Genealogy Society of Santa Cruz County right here in the Monterey Bay area. They also have a DNA Sig that can be found the calendar on their main page at: can identify your DNA matches by parent

If you have a tree at and have added a DNA test to the mix, there is a new tool that might assist you in solving some of those roadblocks.  This tool is still in beta status, but I am sure it is a keeper. 

I have to admit that Gail Burk brought this to my attention, I hadn’t yet seen it.  When she said “You have no idea how stoked I am with this new tool” I figured I had to check it out.

To get to the new tool in the DNA section, go to Ethnicity Estimate, then click View Breakdown under Ethnicity Inheritance. Then move down to “Matches split by parent” and click View Matches.

Ancestry has split your DNA matches by parent! 

They have labeled your matches “maternal” and “paternal” and provided statistics for the two groups.

Let me repeat — You can now see your matches split up by parent.

Ancestry’s new tool is quite accurate.  I had been tagging my matches with color dots to add maternal and paternal groups and have not found any “errors”.  I am not sure how Ancestry is doing this, but you really need to check it out.  Maybe a roadblock is waiting to be solved!!