Dave Oranchak, author of the hugely successful website Zodiac Killer Ciphers, managed to stick a giant monkey wrench in this conclusion with an excellent idea, by suggesting that the Zodiac Killer may have inadvertently missed out a whole line from his cipher. Although this may on first consideration seem less likely, it must be noted that row 17 and row 18 would both begin with the letter "E" in the new presentation. Dave Oranchak came up with an idea for the missing line (shown below left), to which I added a further suggestion (shown below right). The idea behind my suggestion, was utilizing the words chosen by the Zodiac Killer when he threatened to kill more "people" in his July 31st 1969 letters.
#2. In his communication to the San Francisco Examiner, the Zodiac Killer wrote "If you do not print this cipher, I will go on a kill rampage Fry night. This will last the whole weekend, I will cruse around killing people who are alone at night untill Sun Night or un till I kill a dozen people".
#3. In his communication to the San Francisco Chronicle, the Zodiac Killer wrote "I will go on a kill ram-Page Fry. night. I will cruse around all weekend killing lone people in the night then move on to kill again, until I end up with a dozen people over the weekend".
The reason to suspect the missing section of 17 letters/characters would have been "lone or stray people", is because the Zodiac Killer used these exact words in the Vallejo Times-Herald and San Francisco Chronicle above. This suggestion by Dave Oranchak, of the Zodiac Killer accidentally omitting a whole line from his plaintext draught to ciphertext encryption, would have the added benefit of filling 407 of the 408 characters in the cipher.
It is easy to see how the Zodiac Killer may have made this mistake, when his original draught had the letter "E" beginning both row 17 and row 18. A cipher created by the Zodiac Killer using 407 characters out of 408 spaces (arranged 17 X 24) seems far more acceptable. This would have left little room for his identity on the final row, if indeed one was ever meant to be reserved for the final line of the cipher. The only possibility would have been "Z" - now that takes me back a few years.
Thanks to Dave Oranchak.