FOUR DAYS BEFORE JULY 31ST 1969

On July 31st 1969, three parts of one whole cipher were mailed to the Vallejo Times-Herald, San Francisco Examiner and San Francisco Chronicle by the Zodiac Killer, with the latter promising to give us his identity. But what was the inspiration behind the Zodiac Killer mailing letters to three newspapers with part of his manifesto encoded in ciphertext? In his San Francisco communications he spelled his offerings as a "cipher", yet in his offering to the Vallejo Times-Herald he used the variant spelling of "cypher", with the addition of letter "i" to form "cyipher". The Chronicle and Examiner jointly released a Sunday newspaper with a dedicated weekly section called The Puzzle Page, that contained a cryptogram called the Chronicle Cypher. The July 27th 1969 edition supplied us with a 78 character cryptogram, split by message and name, with the answer supplied on page 27. The newspapers puzzle and answer section also contained two variant spellings of the word cipher.

On August 10th 1969, a "concerned citizen" addressed a communication to Sergeant John Lynch of the Vallejo Police Department and supplied the code key to the 408 cipher, stating "Dear Sergeant Lynch. I hope the enclosed "key" will prove to be beneficial to you in connection with the cipher letter writer. Working puzzles criptograms and word puzzles is one of my pleasures. Please forgive the absence of my signature or name as I do not wish to have my name in the papers and it could be mentiond by a slip of the tongue. With best wishes. concerned citizen". The author of this communication (who many believe to be the Zodiac Killer) also gave us a variant spelling (albeit incorrect) of "cryptogram", by using "criptogram". The author also expressed an interest in "word puzzles" on August 10th 1969. So was the Zodiac Killer's inspiration for the July 31st 1969 letters derived from the Sunday newspaper puzzle page?  

Thanks to Cragle for the information used in this article.