Joan Webster's parents made a heartfelt appeal for any information pertaining to their missing daughter, which was broadcast throughout New England on Christmas Day of 1981, less than a month after her disappearance. On January 18th 1982, a $10,000 reward was offered by George Webster's employer, International Telephone and Telegraph Inc, for any pertinent information regarding the disappearance and present whereabouts of the young Harvard graduate.
Gareth Sewell Penn, by some considered a Zodiac Killer suspect, contacted George and Eleanor Webster suggesting that the missing woman may have been the work of the Zodiac Killer. He was convinced that a Santa Claus greeting card was fashioned by the Bay Area murderer, likening it to the November 29th 1966 Confession letter by use of Morse and binary code, along with a whole host of mathematical trickery in a vain attempt to forge a link. However, he was able to receive photocopies of the Santa Claus card and envelope, to which he refers to in a communication retrieved from the FBI files, shown below.
The postmark does not give away its mailing date, but the family made a 1981 Christmas day appeal, followed up by a $10,000 reward on January 18th 1982, in all likelihood, making the deliberately chosen Santa Claus greeting card to be mailed on or shortly after January 20th 1982. That is because I have identified the newspaper cutting from this date, reporting that the family "offer 10G reward for missing coed". I can see no connection to the Riverside murder of Cheri Jo Bates on October 30th 1966, but if I was attempting to forge a link between this greeting card and the Zodiac Killer case, I would start by comparing it to the Christmas card mailed in 1974 to the sister of missing nurse Donna Lass. The 1974 card was addressed to Mary Pilker, a family member of the missing Donna Lass, much the same as the Santa Claus card was mailed to the family of missing Joan Webster. Both women were 25 years of age, and both were still missing when the respective greetings cards were mailed. The 1974 Christmas card contained the cryptic message "Best Wishes, St Donna & Guardian of the Pines", while the 1982 Santa Claus card held the equally cryptic, but typed "Please, where can I write you, ?. SC".