We live in an age of unprecedented access—which not only affects how we view the present but how we see the past. As investigators apply cutting-edge technology to stalled-out investigations, as podcasts uncover fresh leads to old mysteries and true crime books like Michelle McNamara’s posthumously-published title I’ll Be Gone in the Dark help lead to major breakthroughs, cases that once seemed unsolvable are receiving a second look.
One particularly notorious cold case that just may be closer to a solution? The serial murders of the Zodiac Killer.
Beginning in 1968 (though possibly earlier), the Zodiac Killer took the lives of at least five people, and may have claimed as many as 32 more victims. His crimes at least partially inspired the plot of the original Dirty Harry film—released while the killer was still active—not to mention innumerable books and movies, among them David Fincher’s 2007 opus Zodiac, based on the book by Robert Graysmith, a former political cartoonist at the San Francisco Chronicle who dedicated much of his life to finding the identity of the murderer.
While Graysmith’s book and the subsequent film posited who they believed to be likely suspects, the case officially remains unsolved. Yet that may not be the case for much longer. In 2014, Gary L. Stewart, writing with Susan Mustafa, published a book called The Most Dangerous Animal of All: Searching for My Father and Finding the Zodiac Killer. The title comes from the 1932 film The Most Dangerous Game, which the Zodiac Killer quoted in his letters.
Abandoned in a stairwell as an infant, Stewart spent much of his life in search of his biological parents. His quest for his father led him to a man who looked almost exactly like the infamous drawing of the Zodiac Killer’s face, done by a police sketch artist based on a description provided by one of the Zodiac’s only surviving victims.
The story of Stewart’s search for his biological father—with its chilling turn—is reportedly being optioned for film by Campfire, with an eye toward turning The Most Dangerous Animal of All into a documentary. While the book may have helped warm the long-cold Zodiac case, it likely will not bring the killer to justice on its own.
For that, we turn to the same technology that helped put Joseph James DeAngelo, the former police officer believed to be the Golden State Killer, behind bars in 2018. To catch DeAngelo, police used DNA evidence from the crimes along with a genealogy-tracking website (GEDmatch) to create a “family tree” for the killer, from which they could then narrow down suspects.
Now, the Vallejo Police Department hopes to apply a similar approach to finally determine the identity of the Zodiac Killer. During his reign of terror, the Zodiac Killer famously sent coded letters to local newspapers bragging about his crimes, making demands, and threatening future killings. These letters, in no small part, led to the killer’s notoriety. Now they may provide the evidence needed to conclusively identify him.
The Vallejo Police Department sent envelopes that contained two of the letters to a private laboratory for DNA testing in the hopes of finding usable saliva samples. From there, they plan to feed the data into genealogical tracking software, similar to what was used in the Golden State Killer case, and attempt to ascertain the identity of the Zodiac, or at least narrow down suspects. Police departments in San Francisco and Napa County are also reexamining evidence in order to see if advances in DNA and genealogy-testing technology could help shed new light on the case, according to the San Francisco Chronicle.
While the use of genealogy websites to find suspects in criminal cases has drawn concern from consumer privacy groups, there’s no denying that changes in technology from genealogy trackers to the internet itself have changed the way that police–and the public–regard cold cases. Assuming the Zodiac Killer is finally found, whoever he turns out to be, whether Gary L. Stewart’s father, one of the suspects identified by Robert Graysmith, or someone else entirely, it seems unlikely that this is the last time that cold cases will heat back up with the help of dedicated investigators, unflagging true crime writers, and breakthroughs in technology.
Featured photo: Wikimedia Commons