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The Zodiac Killer: facts of an unsolved case
The established facts of the Zodiac Killer case in northern California: the confirmed attacks of 1968 and 1969, the taunting letters and ciphers, the 340 cipher solved in 2020, the main suspect, and why the case remains open.
Between 1968 and 1969, a killer who called himself "the Zodiac" attacked young couples and a taxi driver in northern California, then taunted police and newspapers with letters and coded messages. More than 55 years later, nobody has been charged. This page sticks to what is reasonably well established, not the many theories.
The confirmed attacks
Investigators generally attribute five murders and two attempted murders to the Zodiac:
- 20 December 1968, Lake Herman Road, near Benicia: teenagers Betty Lou Jensen and David Faraday were shot dead.
- 4 July 1969, Blue Rock Springs, Vallejo: Darlene Ferrin was killed; Michael Mageau was shot but survived.
- 27 September 1969, Lake Berryessa: a hooded attacker stabbed Bryan Hartnell and Cecelia Shepard. Shepard died; Hartnell survived and described the attacker.
- 11 October 1969, San Francisco: taxi driver Paul Stine was shot dead. Witnesses saw the attacker, leading to the well-known composite sketch.
The Zodiac later claimed far more victims in his letters, and other cases have been linked to him by some writers, but these are unconfirmed.
The letters and ciphers
From the end of July 1969, the killer sent letters to the San Francisco Chronicle, the San Francisco Examiner and the Vallejo Times-Herald, including details police said only the killer would know. Some letters came with a crossed-circle symbol and the greeting "This is the Zodiac speaking".
- The 408 cipher: split across three newspapers, it was cracked within about a week in 1969 by a schoolteacher, Donald Harden, and his wife, Bettye. It contained a boastful message but no name.
- The 340 cipher: unsolved for 51 years until December 2020, when code-breakers David Oranchak, Sam Blake and Jarl Van Eycke decrypted it. The FBI confirmed the solution. Again, it didn't reveal the killer's identity.
- Two shorter ciphers remain unsolved or disputed, partly because they may be too short to decode with confidence.
The suspects
The best-known suspect was Arthur Leigh Allen, who was investigated for years. He was never charged, and handwriting comparisons and later DNA testing did not link him to the letters. He died in 1992.
Over the decades, private investigators, authors and online groups have named many other people. Some claims received heavy media coverage, but investigators have not accepted any of them as solving the case.
Why the case is hard to solve?
- Multiple jurisdictions: the attacks fell to different police forces, which made co-ordination harder in the 1960s.
- Limited forensics: DNA testing didn't exist. Attempts to recover DNA from envelope seals and stamps have produced only partial or uncertain results, and it isn't certain the killer licked them.
- Hoaxes and noise: copycat letters and thousands of tips muddied the picture.
The case today
The case remains open. The FBI has released many of its Zodiac files through its online records library, the Vault. Advances in forensic genetic genealogy have solved other decades-old cases, which keeps alive hope that a usable DNA profile could one day identify the Zodiac.
Reading about the case responsibly
- Prefer primary documents and reporting from established news organisations over viral claims.
- Be cautious about naming suspects: many people accused online were never charged, and some have living relatives.
- Remember the victims and survivors, who were real people with families.
- Treat dramatised documentaries and podcasts as interpretation, not evidence.
Sources and further reading
Facts checked on 20 October 2026. Spotted an error? Tell us and we will correct it.
Frequently asked questions
What should you know about the confirmed attacks?
The Zodiac later claimed far more victims in his letters, and other cases have been linked to him by some writers, but these are unconfirmed.
What should you know about the letters and ciphers?
From the end of July 1969, the killer sent letters to the San Francisco Chronicle, the San Francisco Examiner and the Vallejo Times-Herald, including details police said only the killer would know. Some letters came with a crossed-circle symbol and the greeting "This is the Zodiac speaking".
What should you know about the suspects?
The best-known suspect was Arthur Leigh Allen, who was investigated for years. He was never charged, and handwriting comparisons and later DNA testing did not link him to the letters.
What should you know about the case today?
The case remains open. The FBI has released many of its Zodiac files through its online records library, the Vault.