A few days ago, I had a nice email from two Swedish engineers called Henrik (Henke) Sundberg and David Thelin: surprisingly, they claimed that they had worked out the details of the Zodiac Killer’s 32-character “map cipher” (also known as “Z32”).

The first thing I did was to put up a new page describing the Z32 cipher, something I’ve been meaning to do for a few years: as normal, I tried to cover the raw factuality and basic observations rather than out-and-out theories and speculation.

The short version is that the letter-shapes in the Z32 cipher look nearly exactly the same as the (famously solved) Z408 cipher, which makes it seem very much as though it too is a homophonic cipher, though with different letter assignments (deciphering it using the Z408 key doesn’t seem to yield anything sensible). Unfortunately, 32 characters (made up of 29 different shapes, i.e. only three appear more than once) wouldn’t normally be anywhere near large enough for a homophonic cryptogram to be cracked, unless you had some significant additional information to work with. (Hint: a cipher key would be a good start. 🙂 )

However, in this case there was some other extra information: a roadmap of the San Francisco Bay Area with a “Zodiac Killer” shape centred on Mount Diablo, and a note saying “The Map coupled with this code will tell you where the bomb is set. You have untill next Fall to dig it up“. A second “little list” letter (posted a month later) give a further clue: “PS. The Mt. Diablo code concerns Radians 4#inches along the radians“.

Sundberg and Thelin’s theory (described in this PDF file) is that it’s in fact a very scientific cipher, as much a stegotext as a cryptogram.


From this, they extract the phrases “C3H3”, “Octane”, and “North of West”, while “HCEL(Zodiac)PW(triangle)” reminds them of how the molecule HClO3 looks, centred around the Zodiac symbol. From which they deduce that they need to look 1 inch (i.e. 6.4 miles) along a vector due West from magnetic North.

Guys, guys… I’m really sorry, but I think you’ve got it wrong. Nobody in their right (or indeed wrong) mind would concoct a chain of reasoning based around a vague resemblance to a particular molecule in order to encode a unit vector. Even dear old Jessica Lee wouldn’t do that, much as she likes chemistry and ciphers.

Look: the Zodiac Killer wasn’t some evil scientific genius, he was a sick, unhappy man with a grudge against the SFPD (probably a surrogate for his sick unhappy relationship with his abusive, distant father) on a gun-powered external power trip, a (literally) vain attempt to right the perceived wrongs in his personal life. I don’t even think he knew properly what a “radian” is, because he doesn’t use the term correctly in his note.

13 thoughts on “Swedish Zodiac Killer Z32 theory…

  1. Michael Moor on January 31, 2014 at 6:38 am said:

    Just a slight correction. “4#inches along the radians” actually reads “& # inches along the radians” as the 4 is really a heavily stylised ampersand.

  2. B Deveson on January 31, 2014 at 1:34 pm said:

    Not any old molecule. An potentially explosive molecule.

  3. B Deveson: a great molecule… but a bit of a stretch to get there from the cipher. 🙂

  4. T Anderson on January 31, 2014 at 3:04 pm said:

    It’s pretty coherent in the land of “Zodiac Theories”. His spelling was bad in general though, so i wouldn’t really assume he didn’t know what it meant. He was obviously stupid from his letters though.

  5. Kaizokugari on January 31, 2014 at 8:50 pm said:

    I’m pretty thrilled to see a Zodiac one come up once in a while! Speaking of which, and taking into account that you’ve said yourself on older postings, that you like more the historical aspect of ciphers rather than the actual solution method, what do you think about the Zodiac case? Although every single evidence pointed out to Mr. Allen from his watch to his typewriter e.t.c. the DNA test on the envelopes didn’t suffice to connect him with the corresponding crimes! I don’t recall a profile extracted by the found DNA sample but it seems rather unlikely for the real Zodiac to have used another mans saliva, foreseeing the imminent discovery of the DNA.

  6. , Rick A. Roberts on February 16, 2014 at 8:17 am said:

    I have posted this elsewhere and would like to post it here also. I believe I have deciphered the Z 32 CIPHER – as to the; CIPHERED part. The message deciphers to ; SIFKLNIRWHDS(END)NGOAOESNBXLTSETDIEI . The message reads; “IS IN FRONT LEFT CORNER NEAR WOODS END AND GO ACROSS SAND BOX LIGHTS SET I DIE”. The Omega sign = END. “K” on first line = “C”.

  7. , Rick A. Roberts on February 16, 2014 at 8:35 am said:

    In relation to the Zodiac Killer “MY NAME IS-” Letter & Symbol Message; I believe I have deciphered it. It reads ; “TENDONLONHONRNTH” or “DON HONRATH”. I’d like people to share their thoughts on this.
    Rick A. Roberts

  8. , Rick A. Roberts on February 16, 2014 at 8:53 am said:

    I have studied The FINAL EIGHTEEN LETTERS sent to three newspapers by Zodiac Killer on August 01 1969. The letters were ; EBEORIETEMETHHPITI . Deciphered this reads ; ENEOLCESEOESTTECSC or ENE OL CE SE OUEST TEC SC . The ENA(ECOLE NATIONALE d’Administration was established in 1945. It allowed French Civil Servants in France to enter politics, science, legal areas more easily than normal. There is a two part exam(Verbal & Written). In my research of the ENA, there had been 5,600 French Senior Officials and 2,600 Foreigners graduate from the ENA(Paris, France Institut d’etudes Politiques) . Could Don Honrath have been a former applicant, non-grad, or graduate of the ENA ?

  9. EBEORIETEMETHHPITI: I pitti them before i met them

    just a guess

  10. bigdoug on January 11, 2015 at 11:07 pm said:

    Just a thought on the map and Mt.Diablo as the starting point. It was indicated that due north was the 0 and to confuse, Z put the numbers 3,6,9. Around the Z symbol. Well 320 degres from the starting point runs through the “SAN FRANCISCO NORTH BAY UNIVERSITY CA” Campus at Santa Rosa exactly 32 letters and 320 degrese from starting point and maybe this is a starting point for the code breakers.

  11. bigdoug on January 11, 2015 at 11:50 pm said:

    Also Santa Rosa lies a few degrese latitude south from lake Berryessa.
    As far as the 340 cypher that has yet to be decoded I beleive he used 3 alphabets.
    There are 26 different symbols as well as a normal alphabet and then there are reversed and lower case and upside down letters making up the 3rd alphabet. Also only some of the cypher has a message with the rest there only to confuse.
    Or and I say Or because he was upset that the first code was broken that this cypher contains no message at all he just wanted to waste the SFPD and newspapers time for not putting him on the front page.

  12. Ok here goes the zodiac is obviously somewhat a learned person if even self studied he uses terminology not everyone would necessarily be accustomed to.I think the spelling errors are indeed purposely there to confuse the authorities on what type of offender they are in fact searching out.the first cipher was a serious attempt at using coded messages to communicate to authorities and hide at the same time. He was surprised by the quickness of which this got cracked.so serious efforts ceased afterward and I think he uses in part serious attempts coupled with nonsense or even a self styled or invented type code that he alone holds the only existing key.he asks about it only once aftet sendong because he knows the code is immpossible to break because he has the key .I think the message is valid but I also think he has made his own code by which it was constructed …just some thoughts

  13. I wonder if there is any discipline which has a habit of adding a ‘hash’ after numbers. I can’t think of any offhand, but this looks as if it is a reflexive habit, and one that isn’t common.
    Radians … 4#inches …..along the radians

    I don’t think he was trained as a carpenter, or astronomer because the instinctive habit there would be to use superscript, not a hash.

    Speaking of ‘hash’ perhaps it is a waiter’s habit [Table 4# 2 fish] ??? Anyone able to enlighten on this?

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