In a video on his Veritasium channel, Derek Muller maps the development of DNA sequencing in the US police. It explains the principles and relates them to specific cases. The video is long, thorough, over a period of several years, and goes into one crucial fact, which can be compared to the time when security forces began using fingerprints to identify perpetrators.
So far, DNA identification of the perpetrator has worked so that you have found one sample at the crime scene and have had to search the database for the same one already paired with a specific person. That is fundamentally changing now. In addition to the police database, databases of private companies also come into play. People contribute to them voluntarily to find relatives, create a family tree and many other reasons.
But as DNA analysis technology has improved, one more important change has taken place. It is no longer necessary to have a DNA sample directly in the database to identify an individual. His distant cousin is enough (and given the millions of DNA samples available in the United States alone, it’s virtually certain you’ll find someone like that).
How many third-knee brantrans do you know?
Then he moves against the flow of time to the first common ancestors, which in the case of the so-called murderer of the Golden State were great-great-great-grandparents. The perpetrator can be any of their descendants, which in this particular case was a group of about a thousand people!
After 44 years, 4 months were enough
Then comes the conventional method and ant detective work. There are a lot of people at first glance, but the police already had a number of clues that quickly reduced the number of suspects. Gender, age, height, stay in the area around Sacramento, later moving to Southern California, etc. The result was a group of only five suspicious men. That’s not enough for investigators to get their DNA samples and convict their culprit with a 1: 1 method.
This is a serial killer from Golden State.
The method of his capture changed forensic science once and for all.
Thanks to this new method, a case that no one has solved for 44 years has been solved by a team of six people in less than five months. This case has paved the way, and since then dozens of murderers from the 1970s and 1980s have been identified in the same way.
“This tool is the biggest revolution since the introduction of fingerprint identification.” summarizes in the video of dr. Connie Bormans, director of the laboratory at Family Tree DNA, which collects and analyzes samples from private individuals.
This is a major shift. The perpetrator is no longer in control if anyone gets to his DNA. In other words, when anyone decides to send their DNA to a database, it points to hundreds of their relatives – living, born a hundred years ago, and those who have not yet been born. Statisticians have calculated that when only 2% of the population puts their sample into the database, 99% of the entire population can be identified.
Good servant, bad lord
This powerful tool in the hands of the police will serve justice, but at the same time there is a fear of its misuse. Example? If the health insurance company got to a detailed DNA analysis and identified a predisposition to some serious illness (= expensive treatment), such a patient would be practically uninsurable, resp. his insurance would be inexpensively expensive.
My privacy is no longer mine. I have no absolute control over it, I share it with my relatives. Don’t I want to publish DNA? Someone can make that decision for me. Maybe he’s already done it…
Once your DNA analysis is made public, there is no going back. DNA is not like a credit card, you can’t block it and have a new one issued.
Watch the video
If you are interested in the topic, I recommend watching the whole video. It contains a number of other interesting details, deals in detail with the moral and legislative aspects of the problem (it mentions the first real conflict) and maps the current market situation: