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Familial DNA Technique Solves 40-Year-Old Murder Mystery


familial DNA

A new cutting-edge technique in familial DNA testing has led police officials to solve a 40-year-old murder mystery. Forensic DNA discovered at multiple crime scenes throughout California between the years 1976 and 1986, has been linked to one genetic profile.

The FBI’s use of their national DNA database is limited to genetic samples of convicted felons, offenders, and people with arrest records. If a perpetrator has a clean record the FBI will not get a hit in the system, and depending on the severity of the crime committed, DNA testing would be needed. The intricacies of familial testing eliminate the possibility of generating false results.

What is Familial DNA Testing?

Familial DNA testing searches for genetic biomarkers that reoccur in specific locations in an individuals forensic DNA structure. During testing to determine a maternal relatedness profile, DNA is extracted from individual mitochondria cells. Designated patterns seen in the Y-Chromosomes are used to identify paternal relatedness profiles. Familial DNA testing connects people unbiasedly by only correlating the genetic makeup of an individual’s DNA sample.

The National Institute of Justice reported:

To date, the United States in its entirety uses the Combined DNA Index System (CODIS) database to collect DNA samples discovered at crime scenes. Accurate DNA matching between two samples consist of both genetic profiles having 20 identical CODIS markers.

The Golden State Killer

In search of the Golden State Killer, California Police officials ran samples from connected cold cases against GEDMatch; a genealogy website that permits users to upload and explore their DNA sequences free-of-charge. Genetic fingerprints left at 12 murders and over 40 rapes led Sacramento County police officers in California to use familial DNA techniques to arrest 72-year-old Joseph James DeAngelo. This enabled them to solve this murder mystery. DeAngelo slipped through all databases with a clean record, and with prior work history in law enforcement familial testing was needed.

Advancements in Familial Testing in New York

The New York DNA database was originally founded in 1996 by the New York State Legislature for limited felony convictions. Since its creation, the New York DNA database has made several advancements in genetic testing including familial DNA testing. Juvenile offenders are exempt from having their DNA collected and imported into the system. The following has been added to the database over a 22 year period:

  • DNA from felony drug and robbery convictions were added in 2000.
  • DNA from terrorist convictions were added in 2004.
  • All remaining felonies were added in 2006.
  • Familial DNA was added in 2017.

After the public outburst by litigators from the Legal Aid Society regarding the legal use of familial DNA testing, Richard Brown, Queens District Attorney explained that:

The New York Division of Criminal Justice Services Commission on Forensic Sciences, delegates to the DNA subcommittee after all protocols are met and a familial search request made by the presiding district attorney and the chief executives ranking highest in the investigating law enforcement agency with jurisdiction.

Intricate techniques in familial DNA testing helped solve a 40-year old murder mystery when all resources were exhausted by the State of California. The use of public websites with disclaimers for public use allows law enforcement to have access to those records.

Written by Jhayla D. Walls


CBC News: A Look at the DNA Testing that ID’d the Suspected Golden State Serial Killer
Department of Criminal Justice Services: About the Office of Forensic Services
National Criminal Justice Reference Service: Understanding Familial DNA Searching: Polices, Procedures, and Potential Impact, Summary Overview
NY Daily News : Legal Aid Lawyers Challenge New Yorks Use of Familial DNA Testing
NBC News: Familial DNA Puts Elusive Killers Behind Bars
SF Gate: The Ingenious and ‘Dystopian’ DNA Technique Police used to Hunt the ‘Golden State Killer’ Suspect

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