DNA and the Search for Justice in the East Area Rapist/Golden State Killer Case

A little over a week ago, DNA evidence was used to arrest Joseph James DeAngelo, Jr. for a laundry list of crimes that occurred from the early 1970’s through 1986. The series of rapes and murders were savage, and captured the imagination and fear of Californians. When would the East Area Rapist/Golden State Killer strike again?

Evidence collected from the crimes sat dormant, including DNA samples that could have identified the suspect. There was no match in the state’s existing DNA data bank of over 2,700,000 suspected felons. Thousands of cold cases were solved from the samples in the state’s system. But not this one. In 2004, California voters approved a ballot measure, Proposition 69, to further expand DNA collection. The law allowed collection of DNA material from all persons arrested (not charged or convicted–just arrested) for a felony. The Supreme Court affirmed the law on the basis that a DNA Search was “justified by an interest in accurate identification,” Justice Leondra Kruger said in the majority opinion. These expanded samples did not contain a match to solve these horrible crimes.

Screenshot 2018-05-03 10.09.02

When the East Area Rapist/Golden State Killer suddenly stopped his attacks, DNA collection and forensic analysis was in it’s infancy. Some suggest that the new crime fighting tool was a major reason that the crimes stopped. DeAngelo was a police officer in two small police departments at the time the crimes were committed. The theory was that if he was the alleged killer, as a cop, he knew that DNA evidence would identify him if he continued–so he chose to stop.

Fast forward to 2018. DNA collection and analysis are so common that television commercials offer DNA testing kits to the public to trace your ancestry and find cultural attachments you never knew existed. On a less trivial level, public testing became available for genetic analysis of hidden diseases, and defects; breast cancer, or health threatening gene mutations. 23andMe, Ancestry DNA, Living DNA and a dozen other companies found thousands of people willing to spit in a vial and mail it off.


image by hoisen via flicker creative commons

The press conference following DeAngelo’s arrest highlighted “innovative” DNA methods used to identify him as the killer in those old cold cases.

DNA was submitted to an open source registry, GEDMatch by a distant relative of DeAngelo to trace their ancestry. Here is where things get interesting from an investigate standpoint. At some point, investigators had to provide a sample of the DNA obtained at one of the crime scenes to GEDMatch and other registries. This crime scene sample turned out to be a familial match to the sample submitted by the relative.

Investigators basically developed their own family tree of the familial match dating back to the 1800’s and methodically traced each branch until they found those in California at the time the crimes were committed. Finally, they focused on one individual–Joseph James DeAngelo. His discarded DNA, from a cup, or some object he tossed in the trash, matched the DNA from the crimes.

GEDMatch is an open source DNA registry, which means there was no expectation of privacy by the distance relative who submitted the sample. Moreover, the open source nature didn’t require a warrant to allow law enforcement to start searching the lineage.

While this is a huge “win” for victims, the use of DNA in criminal process must be balanced with the liberty interests of the accused. Are we sure we got it right? And is the process free from error? We’re talking about lives here–the victims and the accused. There is little tolerance for “wiggle room.”

Factors of crime scene integrity, contamination, chain of custody, transportation, and storage of the DNA samples must be considered. Law enforcement takes these issues into account every day and has processes and procedures in place to make certain the DNA from the crime scene is untampered and pristine.

Can the same be said for private genetics laboratory operations like GEDWeb? You spit in a container, which may, or may not, be handled by multiple people, you mail it off to God know where, and then what processes are used to analyze the sample?


image by tim suess via flickr creative commons

There are cases where these ancestry sites have been unable to differentiate between human and dog DNA. A Chicago news reporter submitted his Labrador Retriever Lucy’s saliva to a well know DNA testing company. While I’m sure Lucy is a very good girl, the lab failed to find that Lucy wasn’t human and actually prescribed a heath regime based on her submitted sample.

The DeAngelo case will raise some very complex and unique legal arguments with regard to DNA testing and analysis. Unquestionably, forensic DNA analysis has resulted in hundreds of cold cases being solved and innocent persons freed. It will remain a critical crime fighting tool. We need to be certain, beyond a reasonable doubt, that the processes we use are sound.

Scales of Justice


  1. […] Author James L’Etoile wrote a fantastic post about GEDMatch, an open source DNA registry used by law enforcement in the DeAngelo […]

  2. Wow. Poor Lucy. 😉 I linked to this post as an update to mine. Thanks for the fascinating article, Jim!

    1. Thanks for the link up, Sue and poor Lucy was committed to a treadmill program and low cholesterol diet. Poor sad Lucy.

  3. […] developments in forensic sleight of hand changed the way investigators look at old unsolved crimes. As we recounted here, DeAngelo was identified after a profile was submitted to an open source DNA database, one designed to flesh out that family […]

  4. […] a distant relative and eventually narrowing the suspect pool down to the potential suspects, like The Golden State Killer, or The Grim […]

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