His next letter, postmarked December 7th 1969 from Fairfield, was shown to be authentic by pre-empting the pleading nature of the Melvin Belli letter and his use of another code of 38 characters. This code contained similar characters to the 340 cipher, unlike the following 13-Symbol and 32-Symbol ciphers. It opened the door to the possibility that the 38 character code was somehow related to the 340 cipher and maybe contained a clue to its construction. Druzer, an avid and diligent Zodiac researcher, mailed me the 38 character code deciphered with the 340 cipher key. The result is mostly garbled, but he drew my attention to the final line of both codes ending in "death". The Zodiac Killer only took a 4+ horizontal combination of characters from the 340 cipher to the 38 character code on two occasions. Those were HER> and AIKꞮ+, which spelled the standalone words of IRON and DEATH before the diagonal shift was applied to the 340 cipher to reveal the message. Despite the last two rows of the 340 cipher being a mixture of forward and backward reading words, the word "death" sits at the end of both the 340 and 38 character ciphers, indicating that this word likely concludes the message in each instance.
Other horizontal words do exist in this format, however, the Zodiac Killer gave us 4 and 5 characters which bound the 340 and 38 character ciphers together, and both formed English words. The Zodiac Killer began and ended his 38 character code with two prominent sections from the start and end of the 340 cipher, both of which contained visible words before any shift was applied (the final word remaining static). This may be another observation, which confirms to the doubters the December 7th 1969 letter as an authentic Zodiac communication. Unless of course, the 38 code hoaxer identified two passages of 4 and 5 characters from the undeciphered 340 cipher, that just happened to accidentally find two English words after the 340 key was applied. This hoaxer would also have to guess that by separating the prominent ZO∆AIKꞮ+ characters on the bottom line of the 340 cipher, into AIKꞮ+ on the bottom line of the 38 character code, he would be reducing these characters to create something meaningful. He apparently did. By separating these characters into the five visible at the end of the 38 character code, he created the word "death", just like the solved 340 cipher. Druzer pointed out the same thing, stating "The most curious/compelling feats are that the author isolated actual words, most notably death, and that he refrained from copying Zodaik, which would certainly be expected of a hoaxer". In other words, he dismantled the ZO∆AIK element, while leaving Ɪ+ in place, to form "death" as the final word on the 38 character code. This appears to show knowledge of the hidden message in the 340 cipher.
The Zodiac Killer was likely reading this newspaper article on November 13th 1969 when he used the wording "There's no doubt I will do my Thing", so it's perfectly feasible that the presence of his 340 cipher prominently displayed within this article, may have been the inspiration to provide further codes based upon its construction. The newspaper article concluded with "Amateur cryptographers by the hundreds were at work trying to decode the cryptogram from Zodiac published in yesterday's Chronicle. It was an amateur - a Salinas teacher - who cracked Zodiac's cipher message in August to which he said the people he killed would serve him as his slaves in paradise. One cryptographer, who has studied the latest message, says it definitely contains word patterns hidden in the 340 symbols. "There is a definite message" he said. "Testing shows it is not just gibberish. Once that is determined then it's just a matter of patience before it pieces itself together". Did the Zodiac Killer take note of this section and provide "bits and pieces" in his next two codes to help in its decryption?