The Golden State Killer: How DNA Solved a 40-Year Mystery

The Power of Forensic Genealogy

By Victor J. Fisher

April 15, 2024

For over four decades, the Golden State Killer terrorized California. He committed at least 13 murders, more than 50 rapes, and over 100 burglaries between 1974 and 1986. Investigators had DNA evidence. They had witness descriptions. They had patterns. What they lacked was a name.

Then, in April 2018, everything changed. Joseph James DeAngelo, a 72-year-old former police officer, was arrested in Sacramento. The method that led investigators to him would transform cold case investigations forever.

The Original Crimes

The Golden State Killer operated under multiple identities before investigators connected his crimes. He began as the Visalia Ransacker, a burglar who terrorized a small California town in the mid-1970s. He then became the East Area Rapist, attacking women in Sacramento and surrounding communities. Finally, he evolved into the Original Night Stalker, committing brutal murders in Southern California.

His methods were meticulous. He would stalk neighborhoods for weeks before striking. He studied his victims’ routines. He disabled porch lights and unlocked windows days in advance. He brought pre-cut lengths of rope. He called victims before and after attacks to ensure psychological torment.

Despite this extensive criminal history, DeAngelo evaded capture for decades. He blended into suburban life, married, raised children, and retired from his job as a mechanic. Neighbors described him as unremarkable.

The DNA Breakthrough

Investigators had preserved biological evidence from the crime scenes for years. As DNA technology advanced, they developed profiles of the unknown suspect. They ran these profiles through CODIS, the FBI’s Combined DNA Index System, without success. The Golden State Killer had never been arrested for a crime that required DNA submission.

The breakthrough came from an unexpected source: consumer genealogy databases.

In 2017 and 2018, investigator Paul Holes and attorney Anne Marie Schubert collaborated with genetic genealogist Barbara Rae-Venter. They uploaded the crime scene DNA profile to GEDmatch, a free public database where people share genetic information to find relatives.

The profile generated matches with distant relatives of the unknown suspect. These were not close relatives. They were third and fourth cousins, people who shared great-great-grandparents with the killer. From these distant connections, investigators built family trees going back generations. They identified branches that could have produced a male born in the right time period.

This process, known as forensic genetic genealogy, narrowed the suspect pool from millions of Californians to a handful of individuals. Joseph DeAngelo emerged as a strong candidate.

Confirming the Match

Identifying a suspect through genealogy was not enough. Investigators needed direct DNA evidence to make an arrest. They conducted surveillance on DeAngelo and collected items he had discarded: a tissue from his trash, the handle of his car door.

The DNA from these items matched the crime scene evidence. On April 24, 2018, Sacramento County deputies arrested DeAngelo at his home.

Lessons for Forensic Investigation

The Golden State Killer case offers several important lessons for modern forensic science.

Preservation Matters

The DNA evidence that solved this case was collected in the 1970s and 1980s. Investigators at that time could not have imagined the technology that would eventually identify their suspect. Their decision to preserve biological evidence made justice possible decades later.

Today’s investigators should assume that future technologies will exceed current capabilities. Every piece of evidence should be collected and stored with that possibility in mind.

Public Databases Create New Opportunities

Traditional DNA databases like CODIS only contain profiles from convicted offenders and crime scene evidence. The Golden State Killer was never in CODIS because he was never caught. Consumer genealogy databases opened a new avenue by allowing investigators to identify suspects through their relatives.

This approach raises privacy concerns that society continues to debate. The balance between investigative power and genetic privacy will shape forensic science for years to come.

Cold Cases Can Be Solved

The Golden State Killer case remained unsolved for 40 years. Victims and their families had given up hope of seeing justice. The arrest demonstrated that determined investigators, combined with advancing technology, can bring resolution to even the oldest cases.

Since 2018, forensic genealogy has identified suspects in numerous cold cases across the country. Families who waited decades for answers are finally receiving them.

The Verdict

In June 2020, Joseph DeAngelo pleaded guilty to 13 counts of first-degree murder and 13 counts of kidnapping. He admitted to crimes spanning 11 California counties. In August 2020, he was sentenced to multiple consecutive life terms without the possibility of parole.

At his sentencing, survivors and family members of victims confronted DeAngelo directly. Many spoke of the decades of trauma his crimes had caused. The courtroom provided a measure of closure that had seemed impossible for so long.

A New Era in Forensic Science

The Golden State Killer case marked a turning point for criminal investigation. It proved that genetic genealogy could solve cases that seemed permanently cold. It demonstrated that time does not protect criminals from justice.

For investigators pursuing unsolved crimes, the message is clear: preserve your evidence, stay current with technological advances, and never stop searching for answers. For those who have committed violent acts, the message is equally clear: your DNA is a permanent record of your crimes. Somewhere in a genealogy database, a distant cousin may unknowingly hold the key to your identification.

The darkness eventually yields to light. Justice may be delayed, but it need not be denied.

Until next time, stay curious, stay vigilant.

Yours in darkness,

Victor J. Fisher