Exercise Parameters and Results

  In late January 2018, I contacted Dr Taylor Berg-Kirkpatrick.  Dr Kirkpatrick suggested a method to validate my proposed methodology.  In a nutshell, the validation would be for me to coerce someone into generating a number of latitude and longitude pairs.  One of these pairs would be a valid location.  Valid meaning a location close to where a school bus could be traveling.  The remaining latitude and longitude pairs would be invalid locations.   All latitude and longitude pairs would be encoded using the same techniques that I believe the Zodiac used.  I would have to determine which of the pairs corresponded to a valid location.


  The outcome of the validation proves the feasibility of my solution.  It doesn’t disprove that other viable methods exist.  However, I contend that a longitude x latitude solution is the simplest, most straightforward method to encode a location in 32 characters.  Other methods would be more complex.




My interpretation of the Zodiac’s Z32:


            CALI <delimiter> longitude value <delimiter> NORTH

  X latitude value <delimiter> WEST <Zodiac signature> <post-script>


You have the opportunity to step into the Zodiac killer’s shoes as he creates the Z32 cipher.  Below are the instructions and restrictions to make the exercise follow the Zodiac’s Z32 clues as closely as possible.  Feel free to forward these instructions and the invitation to others:



  • Provide me with three sets of two strings of characters each consisting of a longitude and latitude value

  • One of the three longitude and latitude value sets will be the location of your ‘bus bomb’, the other two sets can be random values or locations outside of the SF Bay Area

  • The ‘bus bomb’ must be located in the SF Bay Area (SF, Solano, Contra Costa, Sonoma, Alameda, San Mateo or Marin Counties)

  • The bus bomb must be located alongside a road that a school bus might travel (not in the Pacific Ocean, the middle of a rice paddy, a runway in SFO or the top of Mt Diablo)

  • The location must be very accurate.  As the Zodiac stated ‘Radians & inches along the radians..’

  • Either or both the longitude and latitude must be expressed in radians

  • For the sake of this exercise and to make things a bit more challenging for me, the bus bomb need not be located in reference to magnetic north from Mt Diablo (although that is exactly what the Zodiac did)



  • The longitude and latitude may only use characters used in the Zodiac ciphers (Uppercase letters, numbers or Zodiac characters)

  • It is not required to provide your three sets in the form of a complete cipher.  Three sets of longitude and latitude values is acceptable.  If you do chose to emulate the Zodiac and provide a complete cipher, the cipher must follow the form of the Z32: two lines, the second line starts with an ‘X’, geometric shapes or the zodiac symbol delimit the longitude and latitude values.  The character count need not be 32 characters

  • The numerical longitude and latitude values must be encoded using a cipher that existed when the Z32 was created (ASCII, Morse, Baudot, Murray or Bacon).  The dots and dashes of these codes can be either ones or zeros.  Meaning a dot can translate to a zero and a dash a one or vice versa but must be consistent across a value

  • You do not need to use the same cipher method to encode latitude and longitude or across your three sets

  •  If you are aware of another well-known cipher that existed at the time the Z32 was created let me know



  • Refer to the Z32 itself for inspiration

  • The Zodiac used a zero with a dot in it on the second line of the Z32 to represent the leading zero and decimal point of the radian value

  • The Zodiac reversed the characters in the longitude (FMAWKO).  These characters could then be encoded in reverse

  • The Zodiac swapped the longitude and latitude values

  • Converting characters to the numeric longitude and latitude values are the key to cracking the Z32. I propose that the Zodiac counted the 1s and 0s of the ciphers that he used. The longitude and latitude of the Bay Area will preclude the use of some ciphers.  For instance, high values like the 8 or 9 in the longitude would be difficult to create in Morse code (too many 1s or 0s in a row).  Likewise for repetitive values in longitude and latitude.  So even though there are six or so common ciphers, the Zodiac was forced to choose from a subset of the ciphers available. 


Example Encoding (I use the Zodiac’s method updated by tools available to us from the internet)

  1. Start with Google Earth to choose your bus bomb location alongside a road.  Google Earth provides the longitude and latitude in lower right corner. Copy down the degrees, minutes and seconds (DMS) of the longitude and latitude of your bus bomb. 

  2. Convert DMS of both longitude and latitude to decimal degrees using the tool below

  3. Convert decimal degrees on either or both of your longitude and/or latitude to radians using the tool below (Zodiac used radians on the latitude)

  4. Choose one of the ciphers below to encode your latitude (Zodiac used ASCII).  In the Z32, which locates the Zodiac’s bus bomb along highway 12 in Solano County with a latitude of 38 degrees 11’ 10.7”. Convert this DMS latitude using the tool below to decimal: 38.18631 degrees.  The Zodiac happened to convert the latitude to radians (as stated by the Zodiac in one of his clues).  Use the radian conversion tool below if you want. 38.18631 degrees yields 0.66647674 radians.  The Zodiac used ASCII to convert radians to the text in the second line of the Z32.  Refer to the ASCII chart: I translated the O with the dot in it to mean ‘0.’, 66H = f, 64H = d, 76H = v, 74= t.  The characters that you have come up with are your latititude.

  5. Choose one of the ciphers below to encode your longitude (Zodiac used Bacon #1).  Also, in the Z32, Zodiac wrote the characters FMAWKO backwards.  So when we decode, the most significant value lies on the right. Let’s start with a longitude of 121 degrees 48’ 43.6” (west of highway 113).  We again convert from DMS to decimal.  This leaves us with 121.812111 degrees.  The Zodiac may have used Bacon’s cipher.   I’ll follow the Zodiac’s lead and since he reversed the characters, I’ll reverse the decimal degrees: 111218121.   Starting from right to left we need to create a sequence of characters that yield our decimal degrees.   Using the zeros in Bacon’s cipher to generate the numbers and using the ones as delimiters we come up with the following sequence: 01101 01001 10100 00000 01011 00101.  I chose different Bacon characters to generate the sequence of zeros to make my decimal longitude.  Note that there are a few possible character sequences that generate the same sequence of zeros.  If you count the zeros in the sequence above from right to left you end up with 121812111.   Use Bacon’s code to convert each group of five digits of ones and zeros to characters: you get O, K, W, A, M, F. You now have your longitude.   Note:  The forth character in the longitude in the Z32 is a Zodiac character.  The character appears to be a capital ‘J’ back to back with a reversed capital ‘J’.  Zodiac characters are open for interpretation.  The Zodiac threw this special character in just to make things a bit more challenging.  The character could mean anything.  When deciphering the longitude, I ultimately replaced the Zodiac character with ‘W’ (the Zodiac character resembles a ‘W”) after trying other characters that the Zodiac character also resembled like ‘J’ and ‘L’ and an upside down ‘T’.


  1. If you choose to create your own version of the Z32. Embed your latitude into one line of characters using the Zodiac’s Z32 as an example.  The Zodiac put the longitude in the first line, latitude in the second.  You must delineate the beginning and end of your longitude and latitude values.  In the case of the Z32, the zodiac used geometric shapes to separate the values from other text.  The longitude in the first line has a solid square in front and a solid triangle at the rear.  On the second line the latitude follows the ‘X’ and is bounded by the half-filled square. If you don’t add delineators, I will have no way of knowing where your longitude or latitude value starts and ends.  The Zodiac wanted someone to solve the Z32, so he didn’t make it impossible to solve. 

  2. Repeat steps 1 through 6 above for your remaining two invalid entries (or simply use random strings of characters)


  Thanks for helping me validate my proposed solution for the Z32.  Who knows where this will lead?  Solving your submission might lead to corrections in my methodology.  Hopefully it provides new information about the Zodiac killer.   I will attempt to solve your ciphers as they come in.  


Have fun!


  David C


The following links are helpful:


The Zodiac Killer (Zodiac Revisited): Link


Z32 (Cipher Mysteries): Link 

Google Earth Pro: Link


Degrees/Minutes/Seconds to Decimal Degrees (Rapid Tables): Link

Degrees to Radians (Rapid Tables): Link 


ASCII (Rapid Tables): Link

Bacon (ThinkSAAS): Link

Morse (Wikipedia): Link


Baudot & Murray (Wikipedia): Link

Response Ciphers and David C's solutions: