After the abduction and likely murder of Donna Lass on September 6th 1970, the Zodiac Killer mailed two cards. The first was the 13-Hole postcard on October 5th 1970 - notable for the number 13, with a cross pasted underneath. The second was the Halloween card with the number 14 written as 4-TEEN, with a skeleton underneath, in the style of Jesus being crucified on the cross. In both instances, a number written at the top of the cross or crucified form.
When Jesus was crucified, the letters INRI were affixed at the top of the cross above his head: 'Iesus Nazarenus Rex Iudaeorum'' meaning ''Jesus of Nazareth, King of the Jews.'' Bearing this in mind, we shall consider why the Zodiac Killer decided to write 4-TEEN instead of fourteen or 14. There surely must be a reason.
Switching back to 13-Hole postcard, we will place CROSS (a symbol of Christianity) into the code above using the factor of 6 again: CROSS = 18+108+90+114+114=444, exactly the same as Jesus. Could this link our two cards together. JESUS and CROSS together equal 888, reminiscent of the numbers contained within the 13-Symbol cipher, mailed to the San Francisco Chronicle on April 20th 1970. One has to ask, why would the Zodiac Killer paste a cross on the 13-Hole postcard in red, if not the suggestion of a bloodied crucifix?
Halloween or Hallowe'en (a contraction of All Hallows' Evening), also known as Allhalloween, All Hallows' Eve, or All Saints' Eve, is a celebration observed in a number of countries on 31 October, the eve of the Western Christian feast of All Hallows' Day. It begins the three-day observance of Allhallowtide, the time in the liturgical year dedicated to remembering the dead, including saints (hallows), martyrs, and all the faithful departed. Taken from Wikipedia.
The problem we have with the Halloween card, is that the Zodiac Killer has already given us one number - the number 4. This is not present in the system of coding above, based on a factor of 6. So, we will return to basics, where A=1, B=2, C=3, D=4 etc. 4-TEEN = 4 - 20+5+5+14 = 4-44, to give us the figure 444 over the crucified form of Jesus. This now is in tandem with INRI representing Jesus of Nazareth, King of the Jews.
Then some began to spit at him; they blindfolded him, struck him with their fists, and said, Prophesy! And the guards took him and beat him. - Mark 14:65