
The December 7th 1969 and December 16th 1969 Fairfield letters mailed by the Zodiac Killer were almost certainly responses to two newspaper articles published by the Los Angeles Times. A third Los Angeles Times article on December 18th 1969 likely triggered the Zodiac Killer into phoning the San Jose Highway Patrol on December 19th 1969, stating "I am going to kill five of you officers and a family of five between now and Monday". The newspaper headlined with "Cult May Be Linked to Slaying of 2 Girls", incorrectly suggesting a possible connection between the Mansion Family and the murders of Kathie Snoozy & Debra Furlong in San Jose on August 3rd 1969, to which the Zodiac Killer had already claimed on November 8th 1969 when he mailed the Dripping Pen card.
The newspaper detailed the slayings of the Manson Family at the Sharon Tate residence and stated "San Jose detectives developed a possible connection between the cases after conferring with Los Angeles officers. Six members of a hippie clan led by Charles Manson have been charged with murdering five persons. One of the members of the nomadic band, Susan Denise Atkins, 21, is from San Jose. The Manson "family" has visited Miss Atkins' father there". This newspaper article had all the ingredients for the phone call on December 19th 1969. in which the Zodiac Killer may have used the Manson "family" murder of "five" people to concoct the San Jose telephone message of "I am going to kill five of you officers and a family of five between now and Monday".
The newspaper detailed the slayings of the Manson Family at the Sharon Tate residence and stated "San Jose detectives developed a possible connection between the cases after conferring with Los Angeles officers. Six members of a hippie clan led by Charles Manson have been charged with murdering five persons. One of the members of the nomadic band, Susan Denise Atkins, 21, is from San Jose. The Manson "family" has visited Miss Atkins' father there". This newspaper article had all the ingredients for the phone call on December 19th 1969. in which the Zodiac Killer may have used the Manson "family" murder of "five" people to concoct the San Jose telephone message of "I am going to kill five of you officers and a family of five between now and Monday".

It must also be remembered that a comprehensive newspaper article published by the San Francisco Chronicle on August 6th 1969 about the San Jose murders conducted an interview with the father of murdered Debra Furlong, who had a wife and three surviving children. In other words, a remaining "family of five" from San Jose. Probably upset that San Jose law enforcement had mentioned two of Zodiac's claimed victims and were implying a murder link to the Manson Family, it probably wasn't too surprising that he would phone the San Jose Highway Patrol on December 19th 1969 and threaten five officers, just as he had threatened multiple cops in different jurisdictions when he mailed the Fairfield letter on December 16th 1969, just three days earlier.
The Zodiac Killer may have had a long memory, because 8 1/2 years later, a letter mailed to a Los Angeles radio station again threatened to kill two officers and "five" people in total, including Susan Atkins of the Manson Family, whose name featured three times in the Los Angeles Times article on December 18th 1969. On May 2nd 1978, a letter arrived at KHJ-TV in Los Angeles, stating that the Zodiac Killer was "planning to kill five people in the next three weeks", rather than "five of you officers and a family of five between now and Monday". The new threat promised to kill Chief Daryl Gates, Chief Ed Davis, Pat Boone, Eldridge Cleaver and Susan Atkins. The phone call on December 19th 1969, and the letter mailed on May 2nd 1978, were both seemingly inspired by news related to the Manson Family and Susan Atkins, suggestive of one mindset that yearned to kill five.
The Zodiac Killer may have had a long memory, because 8 1/2 years later, a letter mailed to a Los Angeles radio station again threatened to kill two officers and "five" people in total, including Susan Atkins of the Manson Family, whose name featured three times in the Los Angeles Times article on December 18th 1969. On May 2nd 1978, a letter arrived at KHJ-TV in Los Angeles, stating that the Zodiac Killer was "planning to kill five people in the next three weeks", rather than "five of you officers and a family of five between now and Monday". The new threat promised to kill Chief Daryl Gates, Chief Ed Davis, Pat Boone, Eldridge Cleaver and Susan Atkins. The phone call on December 19th 1969, and the letter mailed on May 2nd 1978, were both seemingly inspired by news related to the Manson Family and Susan Atkins, suggestive of one mindset that yearned to kill five.