The Zodiac Killer had threatened schoolchildren when his October 13th 1969 letter arrived at the San Francisco Chronicle. The letter had promised that "School children make nice targets, I think I shall wipe out a school bus some morning. Just shoot out the front tire + then pick off the kiddies as they come bouncing out". The day before this note was thrown towards the young girl from the car, a newspaper article featured in the San Francisco Chronicle on October 20th 1969 entitled Bus Precautions-A Seminar Here on Zodiac Killer, mentioning protection for schoolchildren in many areas. Obviously there is no way to validate if this was the Zodiac Killer responding to this article or just another copycat buying into the Zodiac story.
Bus patrols were widespread after the Zodiac threat on schoolchildren, with newspaper reports detailing the vigilance of authorities as far as the Napa Valley and Santa Rosa. Had the Zodiac Killer ventured just beyond the perceived safety net to fulfil his promise to target schoolchildren, or was this just another sick individual cashing in on the terror experienced in the Bay Area and beyond?
Captain Hays Hickey of the California Highway Patrol had met with authorities on October 20th 1969 to finalize plans for a CHP-Sheriff's Unit Protection on half a dozen or more school buses in the outlying districts of Mendocino County in the wake of Zodiac's threats. Operation Zodiac initially began with three outlying areas covered on October 20th 1969, believing the killer was more likely to threaten areas of a more rural nature.