Before the Algorithm
The Zodiac Killer: confirmed timeline, crime scene dossiers, victim profiles, all four ciphers, and the media machine that made a murderer immortal — before AI entered the picture.
Editorial Notice — This Field Notes brief covers confirmed historical events drawn from law enforcement documentation, verified academic sources, and court records. No accusations are made against any individual, living or deceased. The Zodiac Killer case remains officially open — FBI San Francisco Division.
This Field Notes brief is your forensic architecture for the Zodiac Killer case: a confirmed timeline, crime scene dossiers for each attack, victim profiles, cipher breakdowns, and a media amplification analysis tracing how a local murder became a national obsession. It closes with a primer for the next episode on ciphers and AI.
Part 1 — The Confirmed Timeline
The Zodiac’s confirmed criminal activity spans ten months in 1969, followed by five years of letters. Every event in the graphic below is confirmed and documented. The anchors are fixed. Everything else remains disputed.
The timeline is deceptively simple. Four attacks in ten months, then letters for five more years. The physical violence stopped. The communication never did. That asymmetry — brief violence, extended theater — is the defining behavioral signature of this case.
Part 2 — Crime Scene Dossiers
Each confirmed attack is documented below as a formal case dossier: forensic specifics, known physical evidence, and behavioral analysis. Behavioral observations are drawn from criminological literature and investigative record. They are observations, not conclusions.
Lake Herman Road
The killer parked alongside the victims and waited. A critical detail: 45 minutes of surveillance before the attack. He watched them first. This was not rage. This was patience.
Blue Rock Springs Park
He left, then came back. The pause before the return volley suggests a need to confirm control. The phone call claiming credit is the single most ego-driven act in the case up to this point. He built his own evidence trail.
“He left. He came back. Then he called the police to make sure they knew it was him.”
Lake Berryessa
The most prepared attack in the case: handmade costume, pre-cut rope, rehearsed cover story, planned exit. He retied Hartnell’s hands because Shepard’s knots were too loose. He talked to both victims for several minutes before stabbing them. This was not impulsive.
Presidio Heights
Moving from rural lovers’ lanes to an urban taxi murder signals escalating confidence, desperation, or both. Four attacks, four separate jurisdictions: Solano County, Vallejo PD, Napa County, SFPD. That geographic fragmentation was not accidental.
A consistent thread across all four attacks: the Zodiac communicated after every one. Phone calls, letters, physical evidence mailed to newsrooms. He needed the record to reflect what he had done. Every attack was also a press release.
Part 3 — The Victims
Five people were killed. Two survived. None had any prior known relationship to their attacker. They were teenagers, young adults, a waitress, a music student, and a philosophy grad student — found at a lovers’ lane, a park, a lake, and a cab. What connected them was only circumstance and his proximity.
The Zodiac’s mythology cast them as slaves destined for his afterlife. Their names deserve to outlast his.
Part 4 — The Four Ciphers
The Zodiac sent four coded messages over the course of his correspondence. They were not decorative — each was a deliberate act of power. He wanted the world to know he was speaking. He wanted it to fail to understand what he was saying.
The Z340 — Decoded After 51 Years
In December 2020, David Oranchak, Sam Blake, and Jarl Van Eycke cracked the Z340 using Van Eycke’s AZdecrypt hill-climbing solver and Blake’s 650,000 transposition variations generated in Wolfram Mathematica. The FBI confirmed the solution on December 7, 2020.
“I HOPE YOU ARE HAVING LOTS OF FUN IN TRYING TO CATCH ME THAT WASNT ME ON THE TV SHOW WHICH BRINGS UP A POINT ABOUT ME I AM NOT AFRAID OF THE GAS CHAMBER BECAUSE IT WILL SEND ME TO PARADICE ALL THE SOONER BECAUSE I NOW HAVE ENOUGH SLAVES TO WORK FOR ME WHERE EVERYONE ELSE HAS NOTHING WHEN THEY REACH PARADICE SO THEY ARE AFRAID OF DEATH I AM NOT AFRAID BECAUSE I KNOW THAT MY NEW LIFE IS LIFE WILL BE AN EASY ONE IN PARADICE DEATH”
David Oranchak on the Z13 and Z32: “Cryptanalysis is all but impossible for such a short ciphertext, because solutions are not guaranteed to be unique, and many thousands have been proposed and generally aren’t scientifically falsifiable.” The Z13 claims an identity. It may always claim nothing verifiable.
Part 5 — Media Amplification
The Zodiac Killer case is one of the earliest documented examples of a criminal deliberately engineering media coverage as part of the crime itself. The media was not a passive observer — it was a mechanism the killer used. The ciphers were hooks. The letters were distribution. In 2026, those mechanisms are exponentially more powerful.
“He understood the press cycle of 1969 the way a modern media strategist understands an algorithm. He knew that unsolved, he would never lose the story.”
— Alibis & Algorithms, Season 1 Field NotesThe Zodiac knew that “print it or face consequences” was a story newspapers couldn’t refuse. He knew a symbol reproduced on every front page becomes a brand. And he knew that unsolved, he would never lose the story. In 2026, the case is still generating headlines. His strategy worked.
Next Episode: Code, Computation, and the 51-Year Siege
If this was the story, the next episode is the science. The full technical history of each cipher, why the Z340 was exponentially harder than the Z408, and the story of how three citizen codebreakers finally cracked it using AI-adjacent tools.
- 01If the FBI couldn’t crack the Z340 in 51 years, what specifically did they miss?
- 02What is the difference between a substitution cipher and a transposition cipher — and why does combining both increase difficulty not additively, but exponentially?
- 03Why is a 13-character cipher harder to crack than a 340-character one, even with modern computing power?
- 04What does “hill-climbing algorithm” actually mean in practice — and why was it the right tool when conventional cryptanalysis had repeatedly failed?
References
- Oranchak, D., Blake, S., & Van Eycke, J. (2024). The solution of the Zodiac Killer’s 340-character cipher. Cryptologia, 48(2), 129–157. arXiv:2403.17350
- Bauer, C. P. (2014). Unsolved!: The history and mystery of the world’s greatest ciphers. Princeton University Press.
- Graysmith, R. (1986). Zodiac. St. Martin’s Press.
- Federal Bureau of Investigation. (2020, December 11). Statement regarding Zodiac cipher solution. FBI San Francisco Division.
- Wolfram Blog. (2021, March 24). The solution of the Zodiac Killer’s 340-character cipher. blog.wolfram.com
- Virginia Tech Magazine. (2021). The new cryptographers. eng.vt.edu
