Zodiac killings

Case summary

In 1968–69 at least five murders in Northern California were committed by a perpetrator who called himself 'Zodiac' and mailed ciphered letters to the press. The 340-character cipher was cracked by an independent team in 2020; the perpetrator has never been identified and the case remains open.

Timeline

1. 1968-12-20First confirmed attack on Lake Herman Road: two teenagers killed.
2. 1969-07-04Blue Rock Springs attack; the perpetrator phoned the police.
3. 1969-08-01First cipher letters (Z408) mailed to three newspapers.
4. 1969-08-08Z408 was solved within a week by the Hardens.
5. 1969-10-11Cab driver Paul Stine was killed in San Francisco; a shirt piece was mailed with a letter.
6. 1969-11-08The unsolved 340-character cipher (Z340) was mailed.
7. 2020-12-05Z340 was cracked by Oranchak, Eycke and Blake; it contained no identifying information.
8. 2021-10SFPD confirmed the case remains open and media 'solved' claims are unverified.

People and connections

• ZodiacPerson

  The name the perpetrator gave himself; never identified.

• Paul StinePerson

  Last confirmed victim; scene in Presidio Heights, San Francisco.

• San Francisco ChronicleOrganisation

  Primary recipient of the letters; its archive is a primary source.

• Z340Object

  Transposition-substitution cipher unsolved for 51 years.

• Zodiac to San Francisco ChronicleLetter traffic between 1969 and 1974
• Z340 to ZodiacThe solution confirmed authorship claims but gave no identity

Findings

Every finding lists its source and date. Interpretation stays in the researcher's note.

• Five murders and two attempted murders are tied to the same perpetrator via letter content and scene evidence.

  VerifiedSource: SFPD / FBI Vault1969–1974

• The 2020 solution of Z340 was confirmed by the FBI.

  VerifiedSource: FBI statement2020-12

• A single perpetrator is highly probable; some attributed incidents (e.g. Riverside 1966) remain disputed.

  ProbableSource: Case literature2021

• The 2021 media claim that the killer was identified was not confirmed by law enforcement.

  ContestedSource: SFPD press response2021-10

• No suspect, including Arthur Leigh Allen, has ever produced a definitive physical-evidence match.

  UnverifiedSource: DOJ and case files2026-06

Documents

• DocumentFBI Vault Zodiac filesScanned official paperwork including cryptanalysis correspondence.
• DocumentZ408 and Z340 cipher textsCopies of the original cipher pages mailed to newspapers.
• MapAttack locations mapIncident points in Benicia, Vallejo, Napa and San Francisco.

Sources

1. 01

   Zodiac Killer

   FBI Records: The Vault, 2011, Official file archive

   Open source
2. 02

   Zodiac Killer

   Wikipedia, 2026, Encyclopedia entry

   Open source
3. 03

   The Zodiac Killer's cipher is finally cracked

   The New York Times, 2020, News verification

   Open source
4. 04

   Let's crack Zodiac (Z340 solution walkthrough)

   David Oranchak, 2020, Technical solution write-up

   Open source

Locations

• Presidio Heights (Stine scene)37.79°, -122.46°
• Lake Berryessa attack38.55°, -122.23°

Researcher's note

Interpretation: the Zodiac file shows open-source researchers how code-breaking can be run collectively and verifiably. It is also a warning: dozens of 'definitive suspect' claims have circulated over 50 years and none has cleared the evidence threshold.