showing that the Zodiac Killer may have been committing his crimes based on the 13 Moon Calendar and murdered on pre- ordained dates.
To simplify the reasoning it has been placed in the diagram below, which is based on the 13 Moon Calendar, comprising of thirteen cycles of 28 days to equal 364 days. This calendar can be viewed HERE, but keep the new tab open so you can check the dates of the attacks yourself in the calendar, to see that every single attack occurred on the first day of the week, represented by the crosshair DALI symbol. As stated on the 13 Moon Calendar tutorial the 1st, 8th, 15th and 22nd of each moon will always be a DALI day ie: The first day of each week.
Below are listed 12 attacks. Also note the day of each moon, the first 3 of the 4 confirmed attacks fell in position 8, possibly the origin of the three 8's on the 'My Name is Cipher' mailed on April 20th 1970, but the position 22 of the Paul Stine murder is open to question.
From the first confirmed murders of the Zodiac Killer at Lake Herman Road on December 20th 1968 to the Halloween Card on October 27th 1970, which was taken as a threat of 14 murders, you will see that the disappearance of Robin Graham nineteen days later, if indeed she and Donna Lass were killed, would take the Zodiac murders to 13 and every single one on the first day in a 13 Moon Calendar week.... continued below.
The Little List Letter sent by the Zodiac on 26th July 1970, is the start date of the 13 Moon Calendar, unlike the Gregorian Calendar that starts on January 1st. Incidentally the final victim on this list is Lynn Derrick, that also falls on July 26th.
I cannot find any other victims between December 20th 1968 and November 15th 1970, that fits into the above criteria and completes the list. Any help would be appreciated.
So as to not run over old ground, the complete evolution of this theory can be found, with extra information, via these links in order from 1 to 4.
Thanks to the Law of Time website http://www.lawoftime.org/home.html