The Zodiac Killer mailed three pieces of Paul Stine's shirt, firstly, in the October 13th 1969 letter, secondly, in the November 9th 1969 Bus Bomb letter and thirdly, to Melvin Belli on December 20th 1969, yet no mention was ever given to a fourth swatch of Paul Stine's being received with any subsequent correspondence. The film, up to this point, had been accurate in this respect, so why was it necessary to invent this portion of the story when the Halloween card stood on its own merits as a Zodiac correspondence, being perceived as a personal threat to newspaper reporter Paul Avery. With many previous and current investigators involved in the film, this seemed an unnecessary addition of fiction. Unless of course it wasn't.
The Zodiac did not mail the entirety of the shirt section he removed from the taxicab driver on October 11th 1969, and we have come to believe he wasn't a collector of souvenirs. So why didn't he just mail back the remainder of the shirt in later communications, particularly ones he must have realized would be questioned as authentic correspondence from the killer?
Despite this, in 1970, certain details contained in several correspondences were withheld from publication, most notably the whole of the Little List letter mailed on July 26th 1970, eventually released to the press on October 12th 1970 only two weeks prior to the arrival of the Halloween card. Whether the investigators were trying to force a mistake from Zodiac by 'interfering' with his communications can only be surmised.
The immediate communication after the disappearance of Donna Lass on September 6th 1970 was the Zodiac 13-Hole postcard containing a pasted red crucifix. In later years, a potential burial site was explored by Officer Harvey Hines near Clair Tappaan Lodge, where a rock configuration of 13 stones were positioned in the form of a cross. It was considered that Zodiac may have been pointing us toward the burial site of Donna Lass (the area he had concealed her remains). Was the Halloween card also pointing us toward an area of concealment in a rather more subtle way? The author of the Halloween card had certainly made great effort in creating additions to this card in similar fashion to the 13-Hole postcard, but obviously in a more magnified fashion. What purpose belied the addition of a pumpkin over the pelvis of the first skeleton, as well as adding the second skeleton on the card inner? If indeed this held great purpose, then it was largely missed by most observers. One would like to believe the pumpkin and skeleton were placed on the card for more than just the casual amusement of its creator. That is what we shall investigate.
The Zodiac Killer could have drawn on the Halloween card but chose to add a cut out pumpkin and skeleton. The inside of the envelope contained the phrase "sorry no cipher" twice and was fashioned into an X formation. There may have been no cipher, but was the X marking a location to be found? The pumpkin on the card outer was fashioned over the pelvic region of the skeleton, only to be effectively removed from the skeleton on the card inner to the delight of the author in the form of the word "Boo". Again, an extension of something concealed to the observer before its unearthing. Everything in the card screams out to something hidden that will be revealed. If the Zodiac Killer didn't place a small piece of Paul Stine's shirt behind the pumpkin, it could be argued he missed a Halloween trick - or treat in his case. He drew a colored mask on the eyes of the inner skeleton (that likely in the real world would be made of fabric), that once again hints at concealment.
The Bay Area killer certainly was indicating 14 victims, or a potential 14 victims. However, he also appeared to be emphasizing the number 4. He deliberately separated the number fourteen to create 4-TEEN. He placed four larger eyes close to the pelvic region of the skeleton as if urging us to see something, along with the four dots around the symbol. Could the symbol stand for 'Zodiac Four,' or was it still 'Zodiac Victims Fourteen,' with four attachments to date. The fourth piece of Paul Stine's shirt possibly concealed under the pumpkin by the pelvic region of the outer skeleton, highlighted by the four large eyes imploring us to discover. The Zodiac Killer mailed the Halloween card just after the first anniversary of the Presidio Heights murder, so if he was to send any more pieces of Paul Stine's shirt, this may have been his opportune moment. There appears little reason to conclude this information was withheld by investigators, but it doesn't hurt to consider the possibility.