The author of the 38 character code prominently featured two sections of the 340 cipher, that included the beginning 4 ciphertext characters of the 340 cipher, and the last 5 ciphertext characters of the 340 cipher. The only logical reason for the Zodiac Killer to have done this, would have been to give us a clue to the solving of the 340 cipher. When the code key is applied to the 340 cipher before any period 19 (diagonal shift), the first 4 plaintext characters of the 340 cipher spell IRON. The last 5 plaintext characters spell DEATH. As previously pointed out, a hoaxer would have had to be extremely lucky to keep the beginning and ending of the 340 cipher intact, to the tune of 4 & 5 characters (when creating the Z38), that just happened to create two English words in these notable positions. One would have expected a lazy hoaxer to replicate ciphertext characters 333 to 338 in the 340 cipher, because these characters were close to the spelling of "Zodiac". But the author of the December 7th 1969 letter refrained from doing this, choosing to separate these 6 ciphertext characters, so as to form the word DEATH at the end of the 38 character code.
After the solving of the 408 and 340 cryptograms in 1969 and 2020, there is a strong argument to be had, that the Zodiac Killer's remaining unbroken codes also contain a message, which includes the Z38 mailed just one month after the 340 cipher. I have attempted to tackle the Z38 code, but it needs an expert in code breaking to take a look at this encipherment, such as Dave Oranchak, who I believe could shed more light on this small code. The message beneath - at the very least - should provide a little more insight into the thinking of the Zodiac Killer during this crucial period.
Did the Zodiac Killer create the 38 character code so soon after his November 8th 1969 offering as a prompt to the solution of the 340 cipher? I hope Dave Oranchak will take a look and possibly correct some of the incorrect assumptions I may have made. Thanks to Druzer, a regular contributor to both main Zodiac forums, for his assistance in this matter.
CLICK HERE FOR UNOBSTRUCTED VIEW OF CODE.