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Over 40 years ago, the infamous Zodiac Killer began a series of killings in Northern California that remain unsolved to this day.  During his spree, he mailed letters to local media, boasting about his crimes and taunting the authorities.  In several of these letters, he published mysterious cryptograms containing secret messages.  The first cryptogram was solved very quickly by a high school teacher and his wife.  But the remaining cryptograms (the 340-, 13-, and 32– symbol ciphers) are still unsolved, despite numerous attempts by many people to suggest possible solutions.

The mission of this site is to gather information about these ciphers, and to connect people to tools that might help solve them. This site is also an intersection of computer science, mathematics, classical cryptography, and skeptical thinking. We want to help separate fact from fiction.  And there is plenty of fiction out there.

11 Responses

  1. Joseph Covino Jr
    Joseph Covino Jr · July 19, 2012 at 16:40:20 · →

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  2. bababijan
    bababijan · December 7, 2012 at 23:45:46 · →

    Who said Zodiac’s codes had remained unsolved? Tom (Tommy Toon) Voigt?

  3. Adam
    Adam · July 12, 2019 at 13:11:39 · →


    I have had this hunch or theory for a while… just don’t have the resources to explore it.

    I would like to obtain the crossword puzzles for the papers in which the Zodiac Killer sent communications, in a date range of the days surrounding zodiac events (day of a killing, days leading up to the letter being sent, Sunday before it was sent, full moon prior to 340)

    I would like to remove the letters and just use the grid of the crossword. Superimpose this over the 340 and work the cipher from there… has this been done or thought of before?

    My logic is that it’s a clever, but easy way to conceal a message and a way of tipping his hat to the couple who solved the first cipher. The papers specifically mentioned are ones he has or will have built a rapport with. They say the best place to hide something is right under their nose. This would again be clever, however very easy, and unique way of linking everything together.

    Let me know?

  4. Adam Stoddard
    Adam Stoddard · July 13, 2019 at 04:40:13 · →

    Well I would think 3 dimensionally. Multiple layers of ciphers. Similar to his substitution cipher with multi values.

    Additionally the important message is contained within small text no more then 20 lines. Which is easy to find in a small cross word.

    If you consider other evidence of Xmas/halllween post card. He is artistic. Because of this… The answer is not going to be a name like John Doe. It would be a play on words. Like Jon Dough.

    I also wondered if anybody took the 18 characters from the un- deciphered part of the first cipher and applied them to the 340? It seems very logical, and I would have to think this is already done?

    What would be great is a massive community who shared or reported what methods or techniques have already been applied.

    I have also long wondered if any handwriting experts looked at the 340 and highlighted characters in which there was different pen pressure and strokes. Words with passion would have different markings. After all highlighted characters would gathered, it would shrink the playing field, opening up for cribing and substitutions.

    Someday I am going to get the cross words.

  5. steve
    steve · September 18, 2019 at 01:03:59 · →

    Has anyone tried some sort of spatial analysis (similar to that scene in the movie Contact)? It seems like one could get the zodiac symbol (or something close to it) on most or all of the (horizontal) lines by combining certain symbols (eg – the second line, the 5th and last symbols combined produce it). What happens when the paper would be folded (line by line, perhaps) to form those symbols?

  6. Kari
    Kari · October 13, 2019 at 03:37:37 · →

    Hey David, I sent a message to you on Facebook. Please check your “other” folder. I figured out the gibberish at the end of the Z408 and sent it to you there. I’m anxious to hear what you think. Thanks!!

  7. David C
    David C · January 26, 2020 at 03:01:37 · →

    Is there a way to save the symbols that you type into the cryptoscope? Assuming that you had an idea about the form of the Z340 and input your idea into the cryptoscope, what of the analysis on the cryptoscope page would be most important? In other words, if David Oranchak looked at the tables and charts what would make you conclude that you are looking at a very similar cipher?

  8. RANDY E
    RANDY E · February 26, 2020 at 00:28:23 · →

    I have a pdf file with some information on 340 wher do I attach it

  9. Janet M B
    Janet M B · April 25, 2020 at 05:22:05 · →

    Solution to Z13? I based it on several of his other ones that were allegedly cracked.

    My name is:
    WWII KOREA NAM (i.e. My name is war)

    I believe he was a three times war vet, and it could be that his identity would have been easier to reveal at the time by cracking this code, as well as it symbolically alluding to the significance of war playing a part in the “making of a killer”. At the time, not too many people had gone to these three wars. I’ll get into that later… maybe (I have a theory and I followed a suspects steps to where it ends in CA during the ZODIAC killings)

    How I got to this:

    – He replaces the circle w/x inside with different vowels in this case.
    – He sometimes interchanges W and M; R and M; and A and I; A with W; O with N; N with E; E with W. He sometimes replaces triangles with A or W.
    – He at times has left certain words as is, or almost all of it as is (in this case NAM) to confuse, and in the same way, has used the same letter to replace another- again, to confuse. I also think he misspells to confuse, not b/c he doesn’t know how to spell.

    A = triangle = W = E – N

    A W W I I K O R E A N A M

  10. Chris
    Chris · May 10, 2020 at 16:43:21 · →

    I have possible solutions to the Z13 and 18 random letters at the end of the Z408 Cipher which give you the killers first name, initials and date of birth.

    If you are interested, email me and I will send you the workings?

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