The letters were the worst part. Sure, the killings in the late 1960s were brutal, but the way the guy taunted the police? That’s what stuck. He’d send these cryptograms—four of them total—and brag about how he was "collecting slaves for the afterlife." Creepy stuff. Even now, decades after the last confirmed letter arrived, the hunt for the suspects of Zodiac Killer fame hasn't really slowed down. People are obsessed. They’re looking at DNA, digging up old military records, and arguing on forums until three in the morning. It’s a mess of theories.
Finding a killer who wears a black hood with a crosshair symbol isn't exactly easy when they stop killing for no apparent reason. Or maybe he didn't stop? That’s the thing about this case. Every time someone thinks they’ve found the "one," a piece of evidence doesn't fit. A fingerprint is off. The handwriting is slightly different.
Arthur Leigh Allen: The Only Named Suspect
If you’ve watched the movies or read the books, you know this name. Arthur Leigh Allen is basically the gold standard for suspects of Zodiac Killer investigations. He was a former schoolteacher and a convicted child molester. He lived in Vallejo. He wore a Zodiac brand watch. Honestly, the circumstantial evidence is enough to make your head spin.
When police interviewed him, he had a bloody knife in his car. He claimed it was for chickens. Maybe it was. But he also talked about "The Most Dangerous Game," a story about hunting humans, which the Zodiac referenced in his letters.
The Vallejo Police Department, specifically Sergeant Jack Mulanax, spent a lot of time on Allen. In 1971, Allen’s friend Don Cheney went to the cops and said Allen had talked about killing couples and calling himself "Zodiac" long before the letters started. That’s a huge red flag. Huge.
But here’s the problem. DNA didn't match. In 2002, investigators pulled partial DNA from the stamps on the Zodiac letters. It didn’t fit Allen. His fingerprints didn’t match the ones found on Paul Stine’s cab, either. Does that mean he’s innocent? Not necessarily. Some people think he had someone else lick the stamps. Or maybe the DNA was contaminated. It’s been fifty years, after all.
The Case for Gary Francis Poste
Fast forward to 2021. A group called the Case Breakers made headlines. They claimed they’d identified the killer as a man named Gary Francis Poste. Poste died in 2018, so he wasn't around to defend himself.
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The Case Breakers pointed to scars on Poste’s forehead that they say match the police sketch of the Zodiac. They also claimed that if you remove the letters of Poste’s full name from one of the Zodiac’s ciphers, a new message appears. It sounds like something out of a thriller novel.
Local law enforcement wasn't as convinced. The FBI still considers the case open. The Vallejo Police haven't closed their files. While the Poste theory got a lot of clicks, the evidence is mostly based on photos and "secret codes" that haven't been verified by official cryptographers. Still, Poste fits the physical profile. He was a veteran. He was outdoorsy. He had a temper.
Ross Sullivan and the Riverside Connection
Before the canonical Zodiac killings started, there was a murder in Riverside, California. Cheri Jo Bates. She was killed outside a library in 1966. The Zodiac later claimed credit for her, though the police are divided on whether he was telling the truth or just trying to look more prolific than he was.
Ross Sullivan worked at that library.
He was a big guy. He wore military boots—the same kind of Wing Walker boots that left prints at the Lake Berryessa crime scene. Sullivan disappeared for a while right after the Bates murder. When he popped back up, he looked different. People who knew him said he was deeply disturbed. His sketches look remarkably like the composite drawing from the Stine murder.
The issue? Sullivan had some mental health struggles and passed away in the 1970s. We don't have a clean DNA sample to compare. He remains one of the more chilling suspects of Zodiac Killer history because he was actually there when a very Zodiac-like murder happened.
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Richard Gaikowski: The Journalist Theory
This one is weird. Richard Gaikowski was a journalist. He worked for a paper called Good Times in San Francisco.
Ken Narlow, a detective who worked the case, looked into him. Why? Because Gaikowski’s name—or a version of it ("Gaik")—appeared in one of the ciphers. Also, a dispatcher who took one of the Zodiac’s phone calls allegedly recognized Gaikowski’s voice.
Gaikowski was in the right place at the right time. He had the "intelligence" often attributed to the killer. He knew how to manipulate the media. But "Gaik" is a pretty common string of letters in a random cipher, and "voice recognition" from a call decades ago is shaky at best.
Why the DNA is Such a Mess
You'd think in 2026, we’d have solved this with a simple ancestry kit. It worked for the Golden State Killer, right? Well, it's not that simple.
- Contamination: Back in the 60s, cops weren't wearing gloves. Everyone touched those letters.
- Quality: The glue on the stamps has degraded.
- The "Shadow" Factor: Some experts believe the Zodiac was smart enough to use someone else's saliva or just water to dampen the stamps.
The San Francisco Police Department (SFPD) still has the evidence. They’re reportedly working with labs to use more advanced sequencing, but we’re waiting on a miracle.
The Most Unlikely (But Popular) Suspects
People love a good conspiracy. Some have pointed at Ted Kaczynski, the Unabomber. He was in the area. He liked codes. But the MO is all wrong. Kaczynski was about bombs and anti-technology philosophy; the Zodiac was about personal, face-to-face terror.
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Then there’s Earl Van Best Jr. His son wrote a whole book claiming his dad was the guy. He used handwriting comparisons that looked pretty convincing to a layman, but professional document examiners weren't sold. It felt more like a son trying to make sense of a traumatic relationship with his father than a forensic breakthrough.
How to Track the Case Yourself
If you're looking to dive into the primary documents, you don't have to rely on rumors. The FBI has released hundreds of pages of files through the Freedom of Information Act (FOIA).
- Read the original letters: Look at the misspellings. He spelled "Christmas" as "Christmass" and "paradise" as "paradice." Was he uneducated, or was it a ruse?
- Study the Ciphers: The 408-character cipher was cracked by a teacher and his wife. The 340-character cipher took 51 years to solve, finally cracked in 2020 by a team of amateur codebreakers.
- Check the Maps: The killer mentioned a "Mt. Diablo" code. People are still trying to map out his coordinates using the magnetic north.
The reality of suspects of Zodiac Killer lists is that they are growing, not shrinking. As people die and families clean out attics, "deathbed confessions" and old lockers full of creepy drawings keep surfacing.
What’s Next for the Zodiac Investigation?
Genetic genealogy is the best bet. If the SFPD can get a clean enough profile, they can run it through databases like GEDmatch. They did it for Joseph James DeAngelo. They can do it for the Zodiac.
The clock is ticking. If the killer was 30 in 1969, he’d be nearly 90 now. Most likely, he’s already dead. But the name—the identity—that’s what matters for the families of David Faraday, Betty Lou Jensen, Darlene Ferrin, Cecelia Shepard, and Paul Stine. They deserve a name.
Actionable Steps for True Crime Enthusiasts:
- Review the FBI Vault: Search for "Zodiac Killer" on the FBI’s official FOIA site to read the unredacted reports.
- Support the Cold Case Foundation: They provide resources to underfunded police departments to help process old DNA.
- Scrutinize Source Material: Avoid "sensationalist" YouTube documentaries that claim to have "solved" the case without naming a specific, verified DNA link. Stick to reports from the SFPD or the Napa County Sheriff's Office.
- Monitor the 340 Cipher: Keep an eye on updates from Dave Oranchak, one of the lead investigators who helped crack the most recent code; his work often precedes official police announcements.