A Blast from the Past? Did Zodiac in his 1969 “Bomb Letter Threat” Leave Us a 46-Year-Old Thoughtprint from His Caltech Student Days?

January 7, 2018
Los Angeles, California
“Steve: The Photoelectric Effect thing kind of blows me away. If there were a Nobel Prize for Murder, your dad would have gotten it “
LW (Luigi Warren)










I want to share this recent on-line contribution, which to paraphrase both Zodiac and LW will “positivly ventalate” (sic) one’s mind.
I would agree with LW that the source of Zodiac’s bomb diagram was very likely inspired and can be traced back to George Hodel’s schooldays (1923) at CalTech.
The following “comment” comes from LW (Luigi Warren) one of the regular readers/contributors to the blog site.  LW originally posted the below observations in response to my December 31, 2017, blog: “Critiquing History Channel’s “The Hunt for the Zodiac Killer” and their Discovery that “Zodiac May Be Copycatting the Black Dahlia Murder from 1947?”
LW post-January 6, 2018. He writes:
Just noticed another striking coincidence…
The 1924 Caltech “Big T” annual and 1923 Caltech Bulletin, which cover the academic year GHH spent at the Institute before he was expelled after impregnating a faculty members’ wife, contain several items of potential relevance to his future criminal exploits, e.g.:
1). One-year course in Military Science & Tactics and classes in technical drawing and shop. (Bulletin, p. 86)
2). Work as a reporter and as an editorial assistant, editor “ALFRED A NEWTON.” (“T,” p. 92, p. 94)
3). Scrap-book humor featuring white, hand-drawn lettering & cut-out photographic faces. (“T,” p. 214, p. 219)
4). Possible familiarity with the Riverside area through intercollegiate activities involving Redlands University (e.g., “T,” p. 68)
5). Razzing tradition (“Bookstore is razzed by scientific methods,” “Dorm phone is razzed,” “Assembly cards and Dorm phone are razzed,” etc. (“T,” p. 204-207)
6). Scarlet RIVET “razz sheet.” (“T,” p. 124, see also “T” for 1922, p. 62)
But it gets better. Zodiac’s 1970 “Bus Bomb” diagram is nerd humor — it’s obviously a wind-up. At one level, it’s a classic Rube Goldberg contraption. An example of such can be found on p. 200 of the 1924 “T” (“Automatic spanker for initiates.”) But the diagram also looks like a very Caltech-ish cartoon parody of a physics experiment. Any experiment in particular? Throop College had only very recently been re-invented as Caltech, a world-class scientific institution, at the time your father was admitted as a freshman. In November 1923 the head of the Institute, experimental physicist Robert A. Millikan, was awarded the Nobel Prize for two achievements: his work measuring the charge on an electron, and his experiments verifying Einstein’s theories regarding the Photoelectric Effect. GHH might have covered the attendant celebrations as a reporter for the weekly “Tech.” A comparison of the “Bus Bomb” diagram and a diagram of the apparatus Millikan used to verify the Photoelectric Effect reveals striking parallels: the apparatus comprises an electric circuit including a battery and two plates, with incoming light rays striking one of the plates and controlling the flow of current. The Millikan Memorial library, which today towers over the Caltech campus, was opened in 1967. Perhaps GHH saw it on one of his return trips to Los Angeles, and it brought back memories and thoughts of what might have been.
Thank You, LW for what appears to be another major thoughtprint by way of a “blast from the past.”
Click below link for full handwritten and typed Zodiac bomb letter mailed to San Francisco Chronicle on November 9, 1969.

zodiac bomb ltr pdf

November 14, 1923, Los Angeles Times article announcing Dr. Millikan’s Nobel Prize win.













































  1. Luigi Warren says:

    Steve: Regarding your update on the suspicious poisoning, the Calendar section in the 1924 “T” annual has an entry for Tuesday, February 19, 1924 as follows: “Dorm Rat dies of ptomaine poisoning.” (p. 206). “Ptomaine poisoning” is apparently an old name for food poisoning derived from the misguided notion that it is caused by putrefied meat. Worth noting that Caltech’s enrollment was only 559 students at the time (1923 Bulletin, p. 172). Things that make you go “Hmmm.” -LW

    • Luigi Warren says:

      Steve: On a closer look, pretty sure the “ptomaine poisoning” Calendar entry is just nerd humor. Maybe a case of the college yearbook “razzing” the cafeteria? -LW

  2. Luigi Warren says:


    It’s conceivable GHH harbored animus towards Millikan related to his departure from Caltech and the crashing of his high-flying boy-genius career, and that he got a kick out of perverting or travestying Millikan’s work in the context of the Zodiac terror campaign. Caltech was a very small institution in 1923, and the only layer of administration above the Dean of Freshman was the six-man Executive Council headed by Millikan. Millikan was avowedly Christian and his publicly-expressed views on literature and art might have rankled: “Today literature is infested here and there with unbridled license, with emotional, destructive, over-sexed, neurotic influences” (so, probably not a big fan of Remy de Gourmont, J. K. Huysmans or the Marquis de Sade).

    I notice that Millikan’s key paper on the photoelectric effect focused on determining the value of “h” (Planck’s constant). Maybe too arch even for GHH, but given the Halloween Card contains hints around the letter “H,” there could be a sly joke in there.


    Bulletin of the California Institute of Technology, December 1923
    MILLIKAN: Spokesman for Science in the Twenties, Engineering and Science (CIT Alumni Magazine), April 1969
    A Direct Photoelectric Determination of Planck’s “h,” R. A. Millikan, Phys. Rev. 7, 355, March 1, 1916

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