He’s the ghost of San Francisco. For over fifty years, the shadow of a man in a black executioner’s hood has loomed over Northern California, leaving behind a trail of bodies and a stack of taunting, cryptogram-filled letters that would make a Hollywood screenwriter blush. But this wasn't a movie. It was real. People died at Lake Herman Road, Blue Rock Springs, Lake Berryessa, and in the middle of Presidio Heights. Decades later, the list of suspects for the Zodiac killer remains a chaotic mix of plausible monsters and total dead ends.
Cold cases usually freeze over. This one is boiling.
Why? Because the Zodiac didn't just kill; he performed. He called the police from payphones. He demanded his ciphers be printed on the front page of the San Francisco Chronicle. He claimed he was collecting "slaves for the afterlife." It's heavy, weird stuff that sticks in the brain. Even now, amateur sleuths and professional cold-case investigators are digitizing old files and running DNA on stamp glue, hoping to finally put a face to the name.
Arthur Leigh Allen: The Favorite Who Didn't Fit
If you’ve seen the David Fincher movie, you probably think Arthur Leigh Allen did it. Honestly, it’s hard not to. The circumstantial evidence against him is basically a mountain. He wore a Zodiac brand watch. He talked about killing people with a flashlight attached to a gun. He was near the scenes of the crimes.
Even Dave Toschi, the lead detective on the case, was convinced Allen was the guy.
But there’s a massive, frustrating problem. None of the physical evidence actually sticks to him. His fingerprints? Didn't match the ones found on Paul Stine’s cab. His handwriting? Experts said it wasn't a match for the letters sent to the newspapers. His DNA? When investigators finally managed to pull a partial profile from the stamps in the early 2000s, it didn't look like Allen.
It’s maddening. You have a guy who told his friend, Don Cheney, that he wanted to call himself "Zodiac" and shoot tires of school buses—years before the killings started. Yet, the science says "no." Was he just a creepy guy who enjoyed the attention? Or was he the luckiest serial killer in history? Forensic experts like Kelly Sayre have often noted that circumstantial evidence can be a "trap" that leads investigators to ignore other possibilities. With Allen, that trap was open for decades.
Gary Francis Poste and the Air Force Connection
A few years ago, a group called the Case Breakers made headlines by claiming they’d identified the Zodiac as a man named Gary Francis Poste. He died in 2018. They pointed to scars on his forehead that supposedly matched the police sketch from the Paul Stine murder. They also claimed that if you removed the letters of Poste’s full name from one of the Zodiac’s ciphers, an alternate message appeared.
The internet went wild.
But the FBI and local police didn't budge. They basically said the case remained open. Why the skepticism? Well, the "forehead scars" in the sketch were actually interpreted by many as hair lines or shadows. Plus, the cipher "key" felt a bit like a reach. It’s that classic "Texas Sharpshooter" fallacy where you fire a gun at a barn and then draw the bullseye around the bullet hole.
Poste had a background in the military, specifically the Air Force, which fits the theory that the Zodiac had some kind of technical or code-breaking training. The killer used the Wing Walker boot print at Lake Berryessa—a specific type of military footwear. That's a real detail. But "military background" describes thousands of men in California in the late 1960s. It’s not a smoking gun.
The Dark Horse: Richard Gaikowski
This one is for the deep-cut true crime fans. Richard Gaikowski was a journalist. That’s interesting because the Zodiac was obsessed with the media. He knew how newsrooms worked. He knew how to get a story to the top of the fold.
A man named Blaine Blaine (yes, that was his name) spent years trying to convince the world Gaikowski was the killer. He pointed out that "Gaik" appeared in some of the ciphers. He also noted that Gaikowski worked at Good Times, a counter-culture newspaper in San Francisco, and the Zodiac's letters sometimes mimicked the layout or tone of underground rags.
Even more chilling? Gaikowski was reportedly at the scene of the Paul Stine murder—not as a suspect, but as a "witness" or someone in the vicinity. Some people claim his voice matched the recording of the man who called the police. But again, we hit a wall. Gaikowski was never arrested for the crimes. The evidence is thin, based mostly on coincidences and the fervor of a single whistleblower.
Ross Sullivan and the Riverside Connection
Before the Zodiac was "the Zodiac," there was Cheri Jo Bates. She was murdered in Riverside, California, in 1966. While the Riverside PD has gone back and forth on whether her death is linked to the Zodiac, many investigators believe it was his "origin story."
Enter Ross Sullivan.
Sullivan worked at the library where Bates was last seen. He was a big guy—the police sketches of the Zodiac often describe a "beefy" or "stocky" man. He wore military-style clothing. He was known for being highly intelligent but deeply disturbed. Shortly after the Bates murder, he disappeared from the area.
When you look at Sullivan’s photos, the resemblance to the 1969 sketch is honestly kind of terrifying. He had the thick-rimmed glasses. He had the crew cut. He had the build. But he suffered from mental health issues and died in 1977. Since he was never a primary focus during the height of the investigation, we don't have a lot of the DNA or fingerprint comparisons that we have for Arthur Leigh Allen.
Why DNA Hasn't Solved This Yet
You’ve probably seen cases like the Golden State Killer get solved via forensic genealogy. You take the old DNA, upload it to a site like GEDmatch, and find the killer's great-grand-niece. Boom. Case closed.
So, why hasn't that happened with the suspects for the Zodiac killer?
The problem is the quality of the sample. Back in 1969, nobody knew what DNA was. Police handled the letters with bare hands. They licked the stamps themselves sometimes (seriously). The "Zodiac DNA" we have is likely a mixture of the killer, postal workers, and several detectives.
In 2018, the Vallejo Police Department sent some of the envelopes to a lab for "touch DNA" analysis. We are still waiting for a definitive result that can be used for genealogy. If the sample is too degraded, we might never get that "CSI moment." It’s a bitter pill to swallow for a public that wants closure.
The Cipher Factor: More Than Just Games
The 340 Cipher took 51 years to crack. A team of amateur codebreakers finally did it in 2020. The message didn't contain a name. It said, "I hope you are having lots of fun in trying to catch me."
It’s a slap in the face.
But the fact that it was solved at all tells us something about the killer. He wasn't just a random guy with a gun. He understood transposition ciphers. He understood how to mislead. This points toward someone with a background in mathematics, cryptography, or perhaps the maritime industry. Some theorists suggest Lawrence Kane, who had a history of brain damage from a car accident and supposedly had some cryptology training in the Navy.
Kane is an interesting suspect because he was identified in a lineup by Kathleen Johns—a woman who claimed she escaped from the Zodiac after he abducted her and her baby. But Johns' story has been questioned over the years. Was she really a Zodiac victim, or just a victim of a different, unrelated creep?
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Moving Past the Myths
There are a lot of "fake" suspects out there. People love to claim their dad was the Zodiac on their deathbed. Most of the time, it’s just for attention or a book deal.
To really understand the suspects for the Zodiac killer, you have to look at the overlap of:
- Geographic availability (Was the guy in the Bay Area?)
- Physical description (5'8" to 6'0", stocky, brown hair)
- Technical skill (Could he sew a hood? Could he build a bomb?)
- Psychological profile (The need for control and recognition)
Most suspects hit one or two of these. Very few hit all four. Arthur Leigh Allen hit almost all of them, except the physical evidence. That's the paradox of the case.
What You Can Do Now
If you're genuinely interested in the grit and grime of this case, don't just watch documentaries. The real information is in the primary documents.
- Read the FBI Files: The FBI has released hundreds of pages of Zodiac documents through their "The Vault" portal. It’s dense, but it’s the raw data.
- Study the Ciphers: Websites like ZodiacKillerFacts or ZodiacKiller.com (run by Tom Voigt) have high-resolution scans of the letters. Look at the handwriting yourself.
- Check the Timeline: Use a map to plot the distances between the murders. You’ll realize how much driving the killer did. This wasn't someone who lived in a vacuum; he was mobile.
- Support Cold Case Groups: Organizations like the DNA Doe Project or Othram are the ones actually doing the work to solve these old mysteries. Even if they aren't working on Zodiac specifically, they are perfecting the tech that will eventually catch him.
We might be one lab test away from an answer. Or, we might be looking at a case that remains a mystery forever. Either way, the hunt for the Zodiac killer isn't just about catching a ghost—it’s about the victims who never got to grow old. David Faraday, Betty Lou Jensen, Darlene Ferrin, Cecelia Shepard, and Paul Stine. They are the reason people are still looking.