Here is the decoded 390 character message
"I like killing people because it is so much fun. It is more fun than killing wild game in the forrest because man is the most dangerous animal of all. To kill something gives me the most thrilling experence. It is even better than getting your rocks off with a girl. The best part of it is that when I die I will be reborn in paradice and all the I have killed will become my slaves. I will not give you my name because you will try to slow down or stop my collecting of slaves for my afterlife."
There were misspellings such as forrest, experence and paradice, but this wasn't unusual in the many Zodiac communications, and doesn't change the deciphered character or letter count, fixed at 390. But on the switch from the cipher mailed to the Examiner (cipher 2) to the Chronicle (cipher 3) he appears to actually omit something from his original message. This wasn't a spelling error, but seemed like he lost the train of thought moving from cipher 2 to 3, or from one line to another.
He ended up with "The best part of it is that when I die I will be reborn in paradice and all the I have killed will become my slaves." Was this really his original message, or did he transfer it to the cipher incorrectly?
Was the original message either "The best part of it is that when I die I will be reborn in paradice and all those I have killed will become my slaves" or "The best part of it is that when I die I will be reborn in paradice and all the people I have killed will become my slaves." If so, then his original message would have contained either 392 or 396 characters of legible text. In consequence, leaving only 12 or 16 unsolved characters on the final line of the 408 cipher.
This strikes to the heart of whether the Zodiac Killer originally intended to leave a predetermined identity at the foot of the cipher. He ended up with 18 characters, which to this day remain unsolved. If he had intended to place "those" or "people" in the cipher, but transferred his message incorrectly, then the idea that 18 characters were purposely left to reveal his identity fails to materialize. His new identity would drop to 12 or 16 characters. The 4 consecutive character drop down, from the 8th to 24th line, would also not occur.
In the last article I suggested that the final 18 characters could read "I am the Zodiac Killer", based on his wording in the trinity of July 31st 1969 communications. With the addition of "people" his intended message could have been relegated to the signature "Zodiac Killer" or "I am the Zodiac" With the addition of "those", an altogether different message would likely have been created. His original intention may have been to create a 12 or 16 character message, but was forced to improvise into a longer version, created by the error on line 17. However, this would negate the premise of the previous article to some extent.
To presuppose an original 18 characters being left over for the designated purpose of his identity, would make the assumption that his original message read "The best part of it is that when I die I will be reborn in paradice and all the I have killed will become my slaves," and he transferred it to the cipher correctly.
The idea of a random filler to flesh out a cipher doesn't sit well, when we consider how easy it is to just slightly redesign the message to use all the 408 available spaces. This suggests the 18 unsolved characters do have meaning, and do contain the identity or pseudonym of the Zodiac Killer. This makes more sense than a real name, bearing in mind the author has already decided against this option on lines 18 and 19.
If the Zodiac Killer's original message was 392 or 396 letters in length, he could have created a completely different grid formation with reduced leftovers or none at all, such as 6 rows of 22 characters = 132, mailed to each of three newspapers. This would give us a total of 396. However, he chose to opt for 17 characters in each row, thereby leaving more unused characters. For this reason, there appears a purpose behind the notion of a killer leaving us his identity.
Since he hadn't revealed his pseudonym at this juncture, can we assume that part of the 18 unsolved characters held the words "Zodiac Killer." The precursor of "I am the"- the beginning of the 18 characters, just like the introduction written on the San Francisco Examiner and Vallejo Times-Herald newspapers.
THE 18 UNSOLVED CHARACTERS [PT1]
THE 18 UNSOLVED CHARACTERS [PT3]