Three months after the Little List letter, on October 27th 1970, the Zodiac Killer mailed the Halloween card to the San Francisco Chronicle. The main focus of the correspondence appeared to be directed towards Paul Avery, a reporter at the San Francisco Chronicle newspaper and came in the form of a Halloween card depicting two skeletons.
On the rear of the card the word paradice is crossed with slaves to form four quadrants, where he placed the wording By Fire, By Gun, By Rope and By Knife, of which three had definitely been used in his four confirmed attacks to date. If we include the Modesto Abduction of Kathleen Johns on March 22nd 1970 along Highway 132, then all four are relevant. The card inner also contained the phrase "peek-a-boo you are doomed", an apparent sinister and veiled threat. On the front face of the card, added onto the skeleton's hand, was the number 14, possibly inferring Paul Avery was to become his 14th victim. It must be stressed that the writing on the front of the card was not added by the Zodiac Killer, only the pumpkin. Neither was the "But, then why spoil the game. Happy Halloween" phrase on the card inner. The eye in the tree knothole was not added, with the rest of the card inner added by its author and designer. The Halloween card envelope, either deliberately or inadvertently, contained the name of Paul Avery misspelled to Paul Averly, with the LAV section of his name underlined. On the inside of the envelope (shown in the right sidebar) the author of the card had included the phrase "sorry no cipher" twice, configured in an X formation.
Many theories have been put forward to the meaning of the symbol on the Halloween card envelope and card itself. The Zodiac Killer throughout his correspondence often declared how many victims he had claimed for his afterlife, so quite simply, the symbol could stand for ZVF, indicating a total of Zodiac Victims Fourteen or Zodiac Fourteen, with the four dots alluding to this fact. This would tie in with the running victim total of 4-TEEN placed above the head of the skeleton on the card inner. But why would the Zodiac Killer have decided to write it this way? The answer may be extremely simple. In his victim total of fourteen, the Zodiac Killer by October 27th 1970 had laid claim to the murder of four teenagers, in David Faraday, Betty Lou Jensen, Deborah Furlong and Kathy Snoozy (the latter two of which he claimed by the addition of "Aug" in the Dripping Pen card total of seven on November 8th 1969), and hence the creation of 4-TEEN to incorporate these within his current victim total of fourteen.
The Little List letter was mailed by Zodiac on July 26th 1970, and the 13-Hole postcard on October 5th 1970, both of which claimed 13 victims. The 13-Hole postcard may have contained a repeating victim count because the Little List letter was not published in the newspapers at the time it was received by the San Francisco Chronicle, thereby forcing the murderer's hand in releasing a further communication repeating the same total. The 13-Hole postcard claiming a 13th victim, meant this could not be Donna Lass, who disappeared on September 6th 1970 from the Sahara Tahoe Hotel & Casino - and believed to have been subsequently murdered. The 13th victim was claimed by July 26th 1970, just over a month before the disappearance of Donna Lass.
The Zodiac Killer would ultimately infer his involvement in the Donna Lass disappearance, mailing the Pines card to journalist and reporter Paul Avery on March 22nd 1971, six and a half months later. If he truly was responsible for the abduction and murder of Donna Lass, then she had to be Zodiac victim number 14 as depicted on the October 27th 1970 Halloween card. It would have been seven weeks after her disappearance when this communication arrived, so the choice of an added skeleton could have been more by design than chance. However, if Donna Lass was the Zodiac's 14th victim, then the idea this card was a veiled threat to San Francisco Chronicle reporter Paul Avery is a misguided one.
Often with Zodiac correspondence, he is responding to newspaper articles he has read. Two examples were the Debut of Zodiac letter received by the San Francisco Examiner on August 4th 1969, which was a direct response to two articles featuring Vallejo Police Chief Jack E. Stiltz on August 2nd and 3rd. The Bus Bomb letter on November 9th 1969 was again a direct response to San Francisco Police Chief Martin Lee, who stated the Zodiac Killer was a liar and was not hiding in Presidio Park as he claimed subsequent to his October 11th 1969 murder of taxicab driver Paul Stine - along with the fact he had made several mistakes that night, that included being spotted by three teenagers and leaving fingerprints at the murder scene. In both cases the Zodiac supplied extra details about his crimes to the newspapers in response.
The Halloween card was likely, in part, a response to the newspaper coverage of the Bay Area murderer. The previous newspaper article in the San Francisco Chronicle prior to this card was entitled Gilbert and Sullivan Clue to Zodiac, authored by Paul Avery on October 12th 1970. Therefore, it probably wasn't a surprise when this letter addressed to Paul Avery arrived with the chosen wording "I feel it in my bones, You ache to know my name, And so I'll clue you in". There are other pointers in the San Francisco Chronicle article (although less convincing), such as where Paul Avery writes "Homicide detectives who've been hunting Zodiac for nearly two years frankly admit he is as much an enigma now as he was on December 20th 1968, when he chalked up his first two victims". But whether Zodiac's stylized chalk writing, including the total 4-TEEN, was a direct consequence of the wording in the newspaper article is a matter of opinion.
The article pointed out how the Little List letter mailed on July 26th 1970 plagiarized two acts of Gilbert and Sullivan's The Mikado. The Zodiac wrote "peek-a-boo" around the knothole of the tree on the Halloween card. The British term for peek-a-boo is peep-bo - and peep-bo is a character in The Mikado. There are many newspaper articles by Paul Avery, but the Halloween card was the first one personally addressed to the San Francisco Chronicle reporter, so it is extremely likely that the October 12th 1970 newspaper article was the trigger.
View October 12th 1970 San Francisco article. Click article once opened to magnify.
Two excellent discoveries regarding the Halloween card can be found on Zodiac Killer Site Forum.
 Found it!! By Fire, By Gun, By Knife, By Rope
TIM HOLT COMIC BOOK COLLECTION
The Halloween card was widely assumed to be a direct threat towards Paul Avery, a reporter at the San Francisco Chronicle. Paul Avery found links indicating the Zodiac Killer may have been responsible for the murder of Cheri Jo Bates in Riverside on October 30th 1966, to which the Zodiac either laid claim to, or part indicated his involvement in, by later stating "I do have to give them credit for stumbling across my riverside activity", when he mailed the Los Angeles Times letter on March 13th 1971, five months after this card was received. Whether or not the Halloween card was misinterpreted is open to question, as no threat ever materialized - albeit Paul Avery took no chances in the following months, arming himself at all times with a .38 revolver.
Paul Avery was also heavily involved in the reporting of the kidnap of Patty Hearst (19), a newspaper heiress taken hostage on February 4th 1974 by the Symbionese Liberation Army, an urban militant group. She was later to be viewed as a sympathizer for the group after her involvement in a bank heist, along with other SLA members. She was filmed inside the Hibernia Bank, 1450 Noriega Street, San Francisco on April 15th 1974 brandishing a M1 Carbine, appearing a willing participant in the crime. She was later jailed for two years before being pardoned.
A letter, believed by many, to have been authored by the Zodiac Killer was mailed on February 3rd 1974 from Los Angeles County, one day before the kidnapping of Patty Hearst. According to the FBI files, it wasn't received by the San Francisco Chronicle newspaper until February 14th 1974. This short, seven lined letter is widely referred to as the SLA letter due to the mention of the Symbionese Liberation Army within the correspondence. It is extremely likely this communication was written by the Symbionese Liberation Army or somebody in close alliance with them. The SLA letter began with "Dear" and ended with "a friend". Seven days later, a typed correspondence was mailed by the Symbionese Liberation Army, on February 10th 1974, addressed to the Hearst family or FBI. It too began with "Dear" and ended with "A friend".