These were now direct threats to murder members of law enforcement. Not only had he never done this before, but to this point, no threats on San Jose had ever featured in any published newspaper articles. The San Jose letter mailed on November 21st 1969 also failed to make the newspapers, just like the two Fairfield letters. Yet, three days after the December 16th 1969 Fairfield letter, on December 19th 1969, somebody claiming to be the Zodiac Killer rang police dispatcher Shirley Searey at the San Jose Highway Patrol station issuing two threats that mirrored the contents of the Fairfield letter (despite the fact it was unpublished).
The Fairfield letter, mailed on December 16th 1969, contained the totals of police he wanted to kill. It also contained a picture of a dripping blade entitled The Bleeding Knife of Zodiac. This was effectively an extension of his "by knife" attribution on the car door of Bryan Hartnell at Lake Berryessa on September 27th 1969, glorifying in the fact he was responsible for the brutal stabbing of Bryan Hartnell and Cecelia Shepard alongside the Knoxville Road, as well as the frenzied murder of Kathy Snoozy and Deborah Furlong on August 3rd 1969 in San Jose, which he would ultimately claim by the listing of "Aug" in his running victim count on the Dripping Pen card. The second Fairfield letter was clearly still in his mind (probably angered by its failure to be published), when he made the phone call to Shirley Searey at the San Jose Highway Patrol station on December 19th 1969. He now wasn't threatening to kill one cop in San Jose, he had upped that total to five, more in line with the rest of his list on December 16th 1969. The caller stated "I am going to kill five of you officers and a family of five between now and Monday". The phone call to the San Jose Highway Patrol station and the wording of "you officers", shouldn't leave anybody in any doubt as to where the threat was primarily aimed. Bearing in mind The Bleeding Knife of Zodiac drawing and the focus of the threat toward San Jose, we don't have to go very far to conclude which "family of five" he was threatening.
At the same time he was relegated to the inner pages of two high profile Bay Area newspapers, the murders of the two San Jose teenagers was extensively covered in the San Francisco Chronicle on August 6th 1969. The Zodiac Killer undoubtedly read this newspaper article - and it's probably an understatement to say - he must have been immeasurably displeased. We don't have to look very far in this publication to find the "family of five".
The Zodiac Killer was already claiming the murder of Deborah Furlong, so why not claim he was going to murder the rest of her family for maximum terror. Whether the police connected the dots is unknown, but it's unlikely he arrived at the figure of five randomly. If you look at the August 6th 1969 article here, you will notice the last two subheadings of "callers" and "children".
Under the banner of "callers" it describes the frustration of Glen Furlong (father of Deborah) to the many annoying phone calls the family received, stating "On several occasions people have called and as soon as we answer, they hang up," He said his neighbors were "very sympathetic", but complained he found some of his phone calls "very disconcerting". Under the banner of "children" it lists his remaining children of Glen, 16; Floyd, 12, and Pamela, 11. With the Zodiac Killer having read this San Francisco Chronicle article (his inspiration for the Berryessa attack), it isn't very surprising that the "family of five" threatened by phone on December 19th 1969 would be Glen Furlong and his wife, along with their three children of Glen, Floyd and Pamela.