Zodiac Killer, the serial killer and the subject of thousands of books & movies, has remained America’s most infamous undetected killer since 1968. The Zodiac, accused of murdering at least five people in the San Francisco Bay Area between December 1968 and October 1969, was known for sending letters and cryptograms to the authorities, taking credit for the murders, threatening bombings and more murders if his letters were not printed in the newspaper and describing details known only to police.
Two of the Zodiac Killer’s four cryptograms were decrypted in 1969 and 2020. Investigator Alex Baber, who runs a small team of amateur investigators (known as the Cold Case Consultants of America) determined to unmask the killer’s identity, made a breakthrough when they cracked the killer’s mysterious 13-character string of letters and symbols (known as the Z13 cipher) and shed light on a new suspect, named Marvin Margolis/Marvin Merrill.
In a recent interview with The Times, Alex Baber revealed that the recently released census data and an artificial intelligence program he had developed helped him narrow down the killer’s codes to a 13-letter name: Marvin Merrill.
More on this in our story.
How did Alex Baber find the Zodiac Killer suspect?
After his initial breakthrough, Baber made another discovery. Through his meticulous investigation, Baber was convinced that Merrill was also responsible for the murder of Elizabeth Short, an aspiring Hollywood actress known as “the Black Dahlia” in newspapers, who was found dead two decades before the Zodiac killings. This discovery connected Merrill to not one but two of the most high-profile and unsolved cases in America. While the world chased after the Zodiac, Baber investigated Merrill’s connection with Elizabeth Short, which eventually led him to a chilling discovery.
While Alex Baber had basic information about the Zodiac Killer, white, middle-aged, living in California and 6ft tall, he had the mammoth task of filtering out all the possible arrangements of the alphabet to land on the 13-letter word, which eventually became a suspect in the case. This was where Baber turned to technology and developed an AI program that could analyze military & marriage listings and birth records. The program then narrowed them down to real 13-letter names that fit the repeated characters appearing in the Zodiac Killer’s letters.
After a hard work of nine months, Baber finally landed on the name Marvin Merrill, as detailed in The Times:
“I’d work through the night. I usually operate on two, three hours of sleep as a chronic insomniac.”
Exploring Marvin Merrill’s connection to the Zodiac Killer
Marvin Merrill, considered a suspect in both the Zodiac killings and the 1947 murder of Elizabeth Short (the “Black Dahlia”), was a former U.S. Navy corpsman with medical training who had a romantic relationship with Short before her death.
In 2025, Alex Baber managed to track down Roark Merrill, one of Merrill’s sons and made a chilling discovery that connected his deceased father to the Zodiac Killings. Once Baber detailed his father’s romantic involvement with Short and his suspected involvement in the Zodiac killings, Roark pulled out a 1992 sketch on his phone (named Elizabeth). Roark revealed that the sketch adorned the walls of his father’s office back in the day.
A close inspection and an HD scan of the painting depicted wounds that matched the autopsy reports of Short, as detailed in The Times report:
“When you put it under an HD [high-definition] scanner, you can see the mouth was cut and then covered. What the picture depicted matched the wounds that are documented in the autopsy and crime scene photos of Elizabeth Short.”
However, another chilling discovery came after Alex Baber used the scanner’s colour and contrast filters and found a word hidden behind a dark shading: “ZoDiac”, linking Merrill to the Zodiac Killer. As Roark revealed, the sketch was made just months before Marvin Merrill died of cancer in 1993. Alex Baber considers the portrait as his final confession.
While Alex Baber’s findings positioned Marvin Merrill as a plausible Zodiac Killer, many have questioned his investigation, fueling the ongoing discovery of the unidentified killer.
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Edited by Aashna