The Zodiac Killer was one of the most infamous serial killers in American history, terrorizing the San Francisco Bay Area in the late 1960s and early 1970s. The killer sent a series of cryptic letters and ciphers to local newspapers, taunting police and claiming responsibility for murders. Some of these letters included strange symbols and mysterious coded messages that have never been definitively cracked. Even now, over 50 years later, the identity of the Zodiac Killer remains unknown. But in recent years, advancements in code breaking technology and new analysis of the evidence has brought us closer than ever to finally solving these enigmatic letters.
The Zodiac Letters
The Zodiac Killer sent at least 20 communications to the press and police over his brief but bloody spree. His first letters were sent in regards to the Lake Herman Road and Blue Rock Springs attacks in Vallejo, before he began his infamous letter-writing campaign to local newspapers. The most notorious Zodiac letters and ciphers include:
- July 31, 1969 – Three letters regarding the Lake Herman Road and Blue Rock Springs attacks.
- August 4, 1969 – “Debut” letter introducing the name Zodiac.
- August 7, 1969 – First cipher broken by a high school teacher and his wife.
- October 13, 1969 – Paul Stine murder letter and bloody swatch of Stine’s shirt.
- November 8, 1969 – Dripping pen 340-character cipher (unsolved).
- November 9, 1969 – Bus bomb letter threatening school children.
- December 20, 1969 – Melvin Belli letter.
- April 20, 1970 – “My Name Is…” 13-symbol cipher (unsolved).
- June 26, 1970 – Button letter and map.
- July 24, 1970 – Kathleen Johns letter.
- July 26, 1970 – “Little List” letter quoting Mikado.
- October 5, 1970 – 13-Hole postcard.
- March 13, 1971 – Los Angeles letter reacting to fake Zodiac letters.
- January 29, 1974 – Exorcist letter, last confirmed Zodiac communication.
These infamous letters and the unsolved ciphers within them have confounded law enforcement and amateur sleuths for decades. But with new cryptanalysis techniques and contextual clues, several of these codes may finally be yielding their secrets.
Ciphers and Codes
The most intriguing element of the Zodiac case has always been the killer’s menacing ciphers. Zodiac devised complex coded messages and sent them to local Bay Area papers to demonstrate his intelligence. Some of his ciphers have been solved, while others remain undeciphered to this day.
Solved Codes
408-Character Cipher
The first Zodiac cipher, sent in three sections on July 31, August 4, and August 7, 1969, was solved in a matter of days by Donald and Bettye Harden, a Salinas high school teacher and his wife. The message did not reveal the killer’s identity but did provide details of his crimes and plans for murdering school children.
340-Character Cipher
This complex cipher stymied professional and amateur codebreakers for over 50 years. But in December 2020, an international team used a powerful computing program to finally crack the code. It did not identify Zodiac but reinforced that the killer was the actual author of the letter.
Unsolved Codes
13-Symbol Cipher
Mailed to the San Francisco Chronicle on April 20, 1970, this brief code contains just 13 characters. However, the brevity of the cipher provides few clues for solving it. Some believe it contains the killer’s name.
32-Symbol Cipher
Sent in June 1970, this cipher has just 32 unique characters yet has never been cracked. One possibility is that it contains homophones – different symbols representing the same letters – making it even more difficult to solve.
18-Character Cipher
This string of 18 letters and symbols has also never been decoded. It was sent on November 8, 1969, in a greeting card with a bloody, dripping message warning about the police.
90-Character Cipher
A cipher with 90 unique characters was mailed on July 26, 1970. While containing more symbols to work with, the complexity of the code has prevented cryptanalysts from solving it over the past five decades.
Partial Solutions
Some Zodiac experts and sleuths believe they have solved portions of the unsolved ciphers by matching patterns, frequencies, and statistical consistencies in the symbols. But so far, none have been validated or widely accepted as definitive solutions.
Recent Breakthroughs
In recent years, advancements in cryptanalysis and new contextual findings have provided some tantalizing hints regarding the ciphers.
340 Cipher Finally Cracked
In December 2020, a team of three amateur codebreakers – David Oranchak, Sam Blake and Jarl Van Eycke – finally cracked the infamous 340 cipher, Zodiac’s longest unsolved message. They used a powerful computing program and years of analytical work to decode it. The message did not identify Zodiac but proved the killer had actually written the cipher.
Interpreting the Unsolved Codes
While the remaining ciphers remain uncracked, researchers are using statistical analysis of the symbols and potential homophones to propose tentative solutions for portions of the codes. Some experts believe the 18-character cipher contains information about Zodiac’s identity or residence. The 13-symbol cipher may include the killer’s name.
New Contextual Findings
In addition to advancements in cracking the codes, new context about Zodiac’s life and letters has surfaced in recent years:
- Handwriting analysis suggests Zodiac disguised his writing but slipped up in later letters.
- DNA and fingerprint evidence has excluded some suspects, like Arthur Leigh Allen.
- Isotopic testing matched the paper and envelope ink to local Bay Area postal suppliers.
- The 1997 discovery of a Zodiac watch with the same logo provided a key new link.
- Linguistic patterns suggest Zodiac’s first language was English, not a foreign language.
These findings and more have helped narrow the profile of the Zodiac Killer and provide new leads regarding the codes.
Top Suspects
While the notorious codes remain unsolved, advancements in the case have allowed police to exclude certain suspects and hone in on a handful of prime Zodiac suspects:
Arthur Leigh Allen
One of the earliest suspects, Allen was a schoolteacher whose fingerprints did not match those retrieved from letters. He passed away in 1992.
Rick Marshall
Marshall worked at San Francisco MOMA in the 1960s. His appearance resembles Zodiac sketches, but he was cleared via fingerprint evidence.
Earl Van Best Jr.
The late author proposed his own father was the Zodiac in his book. But most experts have ruled out this suspect.
Ross Sullivan
Sullivan worked at a San Francisco library but no hard evidence definitively ties him to the killer. He died in 1977.
Lawrence Kane
Former Riverside police detective Kane was an early suspect due to his military connections. But no conclusive links were found before his death in 2010.
Gary Francis Poste
A team of independent sleuths recently identified Poste as a potential Zodiac suspect based on new forensic evidence and photos in 2022. Poste passed away in 2018.
| Suspect | Background | Evidence For | Evidence Against |
|---|---|---|---|
| Arthur Leigh Allen | Schoolteacher | Early suspect, lived in Vallejo | Fingerprints did not match |
| Rick Marshall | MOMA worker | Physical resemblance to sketch | Ruled out by fingerprints |
| Earl Van Best Jr. | Author | Claimed his father was Zodiac | Most experts reject claim |
| Ross Sullivan | Library employee | Worked in Riverside in 60s | No hard evidence linking him |
| Lawrence Kane | Ex-police officer | Military connections | No conclusive evidence found |
| Gary Francis Poste | House painter | Scar on forehead matches sketch | Died in 2018, limited evidence |
Conclusion
More than 50 years after the Zodiac Killer first struck terror in Northern California, the infamous case remains open and unsolved. While the 340 cipher was finally cracked in late 2020, his other ciphers, including the 13-symbol code which may contain his identity, continue to confound both law enforcement and amateur sleuths. Promising new advancements in contextual evidence and cryptanalysis provide hope that these codes may someday be solved. And if the name of Zodiac Killer is finally revealed within one of his taunting ciphers, it could bring long-awaited closure and justice in this cold case. But for now, the Zodiac ciphers remain one of history’s most perplexing unsolved mysteries.