The Ecphorizer

My Rosetta Stone
Gareth Penn

Issue #57 (May 1986)

The Zodiac solves his own cipher

I would like to test the patience of the readers of this periodical with one last contribution on the subject of the Zodiac murders. This one, I hope will definitively settle the linguistic questions, specifically the applicability of digital analysis to the Zodiac letters. It would seem to be

The 32-character cipher is a bilingual document...

more appropriate to make such a presentation at the outset rather than five years later, but [quoteright]the document which I will adduce here was not available to me until early 1986, when it was published for the first time in Robert Graysmith's book, Zodiac.

The document in question is the first page of the letter in which the Zodiac killer suggested placing a radian on Mount Diablo. That page ends with a cipher written in 32 characters, which the author says contains information about a hidden bomb. In a letter mailed in late July, 1970, Z refers back to this letter to specify more precisely just what the content of the cipher is:

PS. The Mt. Diablo Code concerns Radians & #inches along the radians

In other words, in the lone case of the 32-character cipher we have evidence from the author as to the contents. Incidentally, the number of inches "along the radians" appears on the second page of the letter, which was read to me in late December, 1980, by Captain Ken Narlow of the Napa Sheriff's Department. On that page, Z says that it is necessary to go four inches along the radian to find the "buried bomb."

I am characterizing the 32-character cipher as my Rosetta Stone for a good reason. The original Rosetta Stone was what linguists call a "bilingual document," in which the same semantic content is given in two languages, one of which is unknown and the other known. The Rosetta Stone was written in parallel texts of Greek, demotic Egyptian, and hieroglyphic writing. Comparison of the Greek text with the two Egyptian texts was what enabled Jean Francois Champollion to make an entry into the ancient Egyptian language. The 32-character cipher is a bilingual document in the sense that its contents are known through another document, the postscript quoted above. By comparison of the analyzed cipher text with the author's description of its contents, we can confirm or discount the applicability of Morse Code and binary numbers as analytical tools. Here is the text of the cipher:

The first step to take in the analysis of a puzzle like this is to number the characters. To my knowledge, no one who has tried to deal with Zodiac ciphers has ever done this. The results of such preparatory labor are invariably rewarding, and this case is no exception.

The first cipher symbol used is the letter C. C is found another time, this one as symbol #26. 1-26 is the range of the Roman alphabet. There are three triangles, appearing as symbols ##2, 12, and 32. This series of numbers has the appearance of one of those missing-number exercises that one finds, among other places, in intelligence tests. The missing number is 22. Now, turning to character #22, we find that is the letter V, which is the 22nd letter of the alphabet. The element of design appears to be rather prominent. If the author has made such a fuss about a particular symbol, it must be important in some way. It is the second member of the three-letter series DVJ, Morse 100 0001 0111. The underlined part is an old friend, binary 130, which appears in the Zodiac literature at every turn. Finding this landmark seems to indicate that we may proceed in the same manner with the rest of the cipher.

The emphasis on letters of the Roman alphabet seemed to me to suggest that this time Z was doing an exercise in rediyision. I substituted Morse Code for all Roman letters and simply passed over the geometric forms, Greek letters, and other signs for which there is no Morse value. The results were highly interesting. Here is a passage from the first part of the cipher read this way: 111001 111010 1110010 1110101. The first six-digit sequence is the binary writing of the number 57. The second six-digit group is binary 58. The next string of seven digits is binary 114, or 57 X 2. The last one is binary 117, or (58 X 2) + 1 — the longitude of Riverside, California, where Z. had murdered a young woman in late 1966, a crime which had not been attributed to the author as of the date of this document, June, 1970.

The letter says that this cipher, together with the enclosed map, will enable the reader to determine the location of the bomb. Graysmith interprets Z's choice of road map, (Phillips 66) as a hint that the author's name may be "Phillips." I suggest that what the map has to contribute is the number 66, the calendar year in which the crime referred to repeatedly in the literature as "117" was committed. The map and the cipher solution, then, combine a location in space (117 degrees west longitude) with a location in time (1966).

The appearance of a series of six- and seven-digit numbers expressing both progressions and doubling would seem in and of itself to be a statistical improbability. The magnitude of that improbability would appear to be reduced to infinitesimal by our knowledge of two things: 1) The Zodiac murdered Cheri Bates in 1966 in Riverside, 117 West; and 2) The value of the radian is between 57 and 58 degrees. In the series, 57, 58, 114, 117, the Zodiac is showing the mathematical relationship between the radian and 117 degrees. But they have something else even more fundamental in common: both longitude and radians are expressions of angular measurement.

Of the expressions contained within the first 25 cipher symbols, I will not discuss any more, mostly for legal reasons, other than to point out the presence of binary 130 in the symbols ##21-23 once again. The total number of digits expressed by Morse analysis through #25 (the H) is 57. Following that, we have the three symbols CEL (##26-28). CEL is Morse 1010 0 0100, which redivides sensibly as 10 10 00 10 0, 2 NINE. This reading is reinforced by the following crossed-circle symbol, (the Zodiac's signature) which is character #29. We have, then, 57 digits expressing, in part, the binary number 57 and its double, 114, followed by "29" expressed two different ways. I submit that the significance of this derives from the fact that the decimalized value of the radian is 57.2958 degrees. Once again, this interpretation might be considered imaginative if it were not for the fact that the author has told us, expliciter, what the contents of this cipher relate to.

In the July 1969 cryptogram, Z used no fewer than seven cipher symbols to stand for the letter E, which is the usual cryptographic entry-point into English-language substitution ciphers. Those symbols, in order of appearance: ZPW+ONE. I don't think it is stretching things too far to read +ONE as "plus one" — since we know that at the time, there was one more murder victim than was accounted for. Here we find PW following the crossed circle, just as the same phrase follows Z in the cryptogram. Z and crossed circles are both expressions of the author's identity, and I read both as subjects of sentences in which PW is the predicate. By alphabetic quantities, P = 16, W = 23. I have pointed out elsewhere that the Zodiac's unsigned confession to the Riverside murder of 29 November, 1966 was written in 1623 letters and that binary 1623 redivides to the Morse spelling of MIKE O.

What about the four inches we are to go along the radian to find the bomb? Z's preference is for metric, not English units. Four inches is 101.59504mm. Here's 101.59504 written to the base two, with my suggested redivisions into Morse Code: 11 00 101. 1 00 11 0 000 10. The Romanized form is MIK.TIMES2. Multiplication of a binary number by two has the effect of adding a zero-suffix. Zero in Morse Code is the letter E. Let me now complete the operation implied by the phrase "four inches": MIK X 2 = MIKE.

I suggest reading the word "bomb" in this context as a figure of speech. We have a related word in the form "bombshell," which my Webster does not even give the secondary meaning of an explosive device. A bombshell is something which stuns, amazes, or upsets, such as a long-ago murder in a distant place kept secret, then revealed, or the cold-blooded shooting of a cab driver for the purpose of constructing an angle of 57.2958 degrees on the face of the earth. The first "bomb" took only four years to explode; the second took over ten years. The third one, also identified in this cipher, has just now begun to explode. 

With this final article, GARETH PENN completes his series exposing the Zodiac mass murderer. Now all that remains is for the authorities to wake up and listen.

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