The Zodiac Killer sent several ciphers to the police and newspapers during his crime spree in the late 1960s and early 1970s. Here are the most well-known ones:
1. The 408 Cipher (Z408)
This was the first cipher sent by the Zodiac Killer, divided into three parts and sent to three different newspapers (The Vallejo Times-Herald, The San Francisco Chronicle, and The San Francisco Examiner) in August 1969. It was quickly solved by a high school teacher and his wife, Donald and Bettye Harden.
I LIKE KILLING PEOPLE BECAUSE IT IS SO MUCH FUN IT IS MORE FUN THAN
KILLING WILD GAME IN THE FOREST BECAUSE MAN IS THE MOST DANGEROUS
ANIMAL OF ALL TO KILL SOMETHING GIVES ME THE MOST THRILLING EXPERENCE
IT IS EVEN BETTER THAN SEX THE BEST PART OF IT IS THAT WHEN I DIE I
WILL BE REBORN IN PARADICE AND ALL THE PEOPLE I HAVE KILLED WILL BECOME
MY SLAVES I WILL NOT GIVE YOU MY NAME BECAUSE YOU WILL TRY TO SLOW
DOWN OR STOP MY COLLECTING OF SLAVES FOR MY AFTERLIFE EBEORIETEMETHHPITI
The last 18 letters, "EBEORIETEMETHHPITI," were never decoded and are believed to be a mistake or a meaningless addition by the killer.
2. The 340 Cipher (Z340)
Sent to the San Francisco Chronicle in November 1969, this cipher remained unsolved for over 50 years. It was finally cracked in December 2020 by a team of codebreakers: David Oranchak, Sam Blake, and Jarl Van Eycke.
The decoded message reads:
I HOPE YOU ARE HAVING LOTS OF FUN IN TRYING TO CATCH ME
THAT WASN'T 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
SO THAT THEY ARE AFRAID OF DEATH
I AM NOT AFRAID BECAUSE I KNOW THAT MY NEW LIFE IS
LIFE IN PARADICE DEATH
3. The Z13 Cipher (My Name Is...)
This short cipher, consisting of 13 symbols, was sent with a letter in April 1970. It is believed to contain the killer's name, but it remains unsolved to this day.
[Cipher symbols, often depicted as a mix of letters, numbers, and astrological signs]
4. The Z32 Cipher (Zodiac's Map)
Sent in June 1970, this cipher was accompanied by a map of the Bay Area. It is believed to contain directions or clues related to a bomb location, but it also remains unsolved.
[Cipher symbols, often depicted as a mix of letters, numbers, and astrological signs]
These ciphers are central to the Zodiac Killer mystery, with only the Z408 and Z340 having been definitively solved. The remaining unsolved ciphers continue to be a subject of intense study and speculation.
And this is with it solved using my method
Applying the Combined Cipher Decoding Methodology to the Four Zodiac Ciphers
Below, I use the detailed, unified cipher-solving process outlined earlier on each of the Zodiac Killer's four main ciphers. For the two solved ciphers (Z408 and Z340), I summarize how the process works and why it succeeded. For the unsolved ciphers (Z13 and Z32), I describe how the same process would be applied and what obstacles remain.
1. Z408 Cipher ("I LIKE KILLING PEOPLE...")
Cipher Type: Homophonic substitution
Process Applied:
Acquire Cipher: The cipher was split into three parts, each a grid of symbols.
Frequency Analysis: Analysts noted multiple symbols for common letters (e.g., "E" had seven symbols).
Segmentation: Each part was treated as a separate block.
Homophonic Substitution: Donald and Bettye Harden matched symbol frequencies to English letter frequencies, using cribs like "KILL" and "SLAVES."
No Transposition: The cipher was a straightforward substitution, so no grid rearrangement was needed.
Result: The plaintext was revealed as the killer's message about killing for fun and collecting slaves for the afterlife.
Remaining Mystery: The last 18 letters ("EBEORIETEMETHHPITI") did not fit the pattern and remain unsolved—possibly a meaningless addition.
2. Z340 Cipher ("I HOPE YOU ARE HAVING LOTS OF FUN...")
Cipher Type: Homophonic substitution + transposition
Process Applied:
Acquire Cipher: 340 symbols in a 17x20 grid.
Frequency Analysis: 63 distinct symbols, with multiple symbols per letter.
Segmentation: The grid was split into segments, including a special "LIFEIS" segment, based on mathematical criteria and pattern analysis.
Homophonic Substitution: Initial symbol-to-letter assignments were made based on frequency, then refined.
Transposition: The solution required a "1,2-decimation" transposition, skipping the "LIFEIS" segment and reading other parts in a specific order.
Computational Heuristics: Tools like AZdecrypt and custom algorithms tested billions of permutations, using English language scoring and cribs to guide the solution.
Result: The plaintext was revealed, matching the Zodiac's taunting style and confirming the killer's authorship.
3. Z13 Cipher ("My Name Is...")
Cipher Type: Short homophonic or mixed substitution (13 symbols)
Process Applied:
Acquire Cipher: 13 symbols, possibly letters, numbers, and astrological signs.
Frequency Analysis: Limited by short length; frequency analysis is not effective.
Segmentation: Not applicable due to short length.
Homophonic Substitution: Attempts to map symbols to letters using possible Zodiac-related cribs (e.g., "ZODIAC," "KANE," "ALLEN").
Transposition: With so few symbols, transpositions yield too many possibilities for meaningful brute-force analysis.
Computational Heuristics: Dictionary and name-matching algorithms have been tried, but no solution has been confirmed.
Result: Remains unsolved, likely due to its brevity and possible use of a private or one-time cipher key.
4. Z32 Cipher ("Map/Bomb Cipher")
Cipher Type: Short homophonic or mixed substitution (32 symbols)
Process Applied:
Acquire Cipher: 32 symbols, possibly letters, numbers, and astrological signs.
Frequency Analysis: Limited effectiveness due to short length.
Segmentation: Some researchers have tried splitting the cipher based on the map grid or possible geographic clues.
Homophonic Substitution: Attempts to map symbols to letters using possible bomb-related cribs or Zodiac phrases.
Transposition: Some have tried rearranging the symbols based on the map's coordinates or grid.
Computational Heuristics: Automated tools have tested thousands of key possibilities, but no coherent English message has emerged.
Result: Remains unsolved, possibly due to brevity, a one-time pad, or a non-standard cipher method.
Summary Table
Cipher Solved? Method Used Outcome
Z408 Yes Homophonic substitution, cribs, frequency Full plaintext revealed except last 18 letters
Z340 Yes Homophonic substitution, transposition, computational heuristics Full plaintext revealed after 51 years
Z13 No Homophonic substitution, cribs, heuristics Unsolved—too short, possibly a name or code
Z32 No Homophonic substitution, transposition, heuristics Unsolved—possibly map-related, too short
Conclusion
The combined methodology—frequency analysis, segmentation, homophonic substitution, transposition, cribs, and computational heuristics—has proven effective for long, patterned ciphers (Z408, Z340), but is limited by the brevity and possible nonstandard construction of the shorter ciphers (Z13, Z32). For Z408 and Z340, the process revealed the Zodiac's chilling messages. For Z13 and Z32, the same approach has not yielded a solution, likely due to insufficient data and/or unique cipher design.
If you want to run a specific custom cipher or have further details about your own cipher pattern, I can help you apply this process step-by-step to any Zodiac cipher text.