The San Francisco Chronicle ran an article on the same subject on November 8th 1969, stating "The string of sadistic calls began on October 23rd. On one occasion, the caller told Williams he had gone to a Martinez school in search of victims but had left when he found police there. Another time, the teacher said the caller, whose voice he described as muffled as if speaking through a handkerchief, said he was going to "kill the lady in the blue house".
The arsenic laden drink was discovered on November 2nd 1969. This may not have been the Zodiac Killer, however, this threat was seemingly backed up.
The article ran in the San Francisco Chronicle on November 8th 1969, so if this was the Zodiac, he may have been unaware at the point he mailed the 'Dripping Pen' card on November 8th as to whether his deadly attack had been successful. He mailed the "poison pen" letter on the same day and declared "I thought you would need a good laugh before you hear the bad news. You won't get the news for a while yet". Clearly, had Daniel Williams died from the poisoning, he may not have been discovered immediately. The style of attack would also conform to Zodiac's new declaration on November 9th that "I have grown rather angry with the police for their telling lies about me. So I shall change the way the collecting of slaves. I shall no longer announce to anyone. When I committ my murders, they shall look like routine robberies, killings of anger, + a few fake accidents, etc".
The threatening phone calls and attempted murder of this high school teacher would precede the second cipher offering from the Zodiac. An offering accompanied by what could be interpreted as a "poison pen" letter. The Zodiac Killer's first cipher was cracked in a matter of days by Donald Gene and Bettye June Harden. Don Harden began teaching at North Salinas High School in 1960. There is slim chance this was Zodiac, but it doesn't hurt to explore every angle.
It was memorialized in music by French singer Maxime Le Forestier in 1971, inspired by his time living in the blue house with a hippie commune called "Hunga Dunga". 'Maxime Le Forestier spoke of the house where everyone was welcome, where Tom, Phil and Psylvia lived. The house was in fact home to the Hunga Dunga commune, and several of the people mentioned in the song still live in the Bay Area'. Mission Local.
Could Daniel Williams have been Zodiac's intended eighth victim, and was the 'Bus Bomb' letter on November 9th 1969, stating "This is the Zodiac speaking up to the end of Oct I have killed 7 people" so precisely, indicative that an eighth victim was yet to be discovered, somewhere between October 31st 1969 and the date of this letter. The fact that Zodiac made a point of highlighting the "end of Oct" in the Bus Bomb letter, rather than just stating "to date I have killed 7 people" is extremely suggestive that we hadn't "heard the bad news yet".