Am definitely late coming around to the idea of Zodiac being tied to the Santa Rosa Hitchhiker murders, thought at first there could be no way, but have become increasingly convinced he is. Think he is alive, he lived most/all of his life in CA; he is likely first-generation American; he was/is married and was employed in academia with some focus/interest in music/theater; background in high school sports, university educated, perhaps some military; and some tie to Sonoma vineyards; think he had meaningful and long-lasting connections to the Santa Rosa area and Saramento area, and do think he murdered Cherie Bates. I think he is involved in the SRHMurders in some role, think he is behind the murder of Carolyn Davis. Carolyn Davis per some sources noted she'd witnessed a double murder in Shasta County, that sounds very much like a potential Zodiac situation. And strychnine was historically used on vineyards to control gophers and voles, (Believe the EPA put an end to such use in 1972.) Moreover, there was some symbol reminiscent perhaps of Zodiac near Carolyn's site. Don't know if he was involved in other/all the SRHMurders, but I know Lori Kursa may have had two attackers per sources. While I can't picture "Zodiac" allowing cooperation in his crimes, I can maybe picture him participating in such crimes with his partner/s completely unaware they were cooperating with-- Zodiac. Meaning his cohorts would be aware he was a murderer, but not "that" murderer, not Zodiac.
It's theoy only and there are a lot of other theories on other threads RE: the strychnine which make a lot of sense, and no relation to Zodiac.
I do think at the very least, though, that Zodiac had at least "some" involvement in the SRHMurders.
