As usual, this is not a claim to the solution, just an idea that could possibly be added to by contributors or simply discarded as unlikely. Some, but not all, of the following has been covered in previous posts.
From the start of his murderous campaign on December 20th 1968, until the 13 Hole Postcard on October 5th 1970, twelve out of the thirteen victims closely associated with the Zodiac case had either disappeared or been murdered on the first day of the 13 Moon Calendar week. To view how this calendar works visit here for a brief explanation.
Below is the list compiled previously, along with the Zodiac's confirmed four attacks.
It was then shown that one of the most noticeable features that resided on the 340 Cipher, was the near use of the name Zodiac on the final line and it was conjectured that this may have been a clue to his third cipher, when the My Name is....Letter arrived five months later on April 20th 1970, thereby continuing the theme of numerology.
Since the Zodiac Killer exhibited all the traits of an egotist, it would not have been unusual for him to use his own moniker as a Key and by placing this key alongside the apparent use of his name on the 340 Cipher, we may find an answer. So by using simple mathematics and no massive leaps of faith, we shall count numerically the difference between the respective six columns. The first three letters produce three 0's and the second three letters produce three 8's. Now circle the three 8's with the three 0's, to construct the feature found within his next cipher. Also note the positioning of the Zodiac crosshair and the upside down Aries symbol in relation to both ciphers. SEE DIAGRAM BELOW.
The day after the 340 Cipher, the Zodiac Killer mailed us his Bus Bomb Letter. At the foot of this correspondence, he drew us a crosshair and placed five X's on its circumference. It has been thought that this may indicate the location points of his crimes. When this crosshair is placed over a map of Northern California, centered on Mount Diablo, three of the lines pass over the Vallejo region, Lake Berryessa and the upper portion of San Francisco. See here.
So far we have the first three attack dates falling on the 8th day of the 13 Moon Calendar, the final three letters of Zodiac producing the 888 numerology to carry onto the My Name is....Cipher, so lets examine the first three murders of Betty Lou Jensen, David Faraday and Darlene Ferrin, all murdered in close proximity to one another.
The final cipher was sent to the San Francisco Chronicle on June 26th 1970, known as the Button Letter. Accompanying this letter was a map of San Francisco and its vicinity and drawn on this map was a crosshair, with the numbers 0, 3, 6 and 9.
Lets now apply those numbers to the Bus Bomb Letter, along with the remaining 'clock face' and again reapply this onto the map, centered over Mount Diablo. The first three murders of Betty Lou Jensen, David Faraday and Darlene Ferrin, all fall on position 8 of the clock face, with another link to 888.
It should also be noted, the Zodiac Killer intentionally separated his 408 Cipher into three parts of 8 lines after committing his first three murders.
The number 888 represents Jesus in biblical numerology, it may also have been subtly placed within the Zodiac's own moniker on the 340 Cipher. Jesus has also been referred to as 'I am', using this in declarations about himself many times. SEE HERE for explanation.
Was it possible the Zodiac was influenced by religion in his crimes and a possible link to 888.
The 340 Cipher was his masterpiece of creation, to this day undeciphered, but was it in any way holding a secret to the identity or possible driving force behind America's most infamous serial killer.
Was it possible he opened up with the first line from Genesis ' In the beginning god' and ended it with a signature from Jesus, or the Zodiac, beholding the 888 hidden within its encryption and signifying that his search for the perfect afterlife was just getting started.