The Zodiac Killer Z32 Cipher and the Rule of Three
On November 25, 2014, a user identified as Mr. Lowe initiated a forum thread titled Zodiac Month Clock Theory on a now-defunct website formerly operated by Mike Morford. In this thread, Mr. Lowe interprets the Zodiac's crosshair symbol found in the November 9, 1969, letter — crosshair annotated with five X’s—by assigning each X to a calendar month.
From this framework, he identifies links to a historical scientific advisory group known as JASON.
Prior to encountering this thread, I was unfamiliar with the JASON organization and consequently undertook independent research to better understand its origins, structure, and purpose. That inquiry led me into broader topics, including Alfred Loomis, the development of microwave radar, and the history of aerial navigation. Some of the information I encountered is relevant to what follows.
During an exchange with Mr. Lowe, he questioned my reference to a “4-inch” measurement. I clarified that I believed the Zodiac's crosshair on the Phillips 66 map he provided—marked with the numerals 3, 6, and 9—was constructed to scale using the reference scale printed on the bottom of the Phillips 66 map. It appears the Zodiac may have employed a circle template, rendering a symmetrical crosshair with a diameter of approximately four inches.
This measurement prompted a key realization: the intended location of the supposed bomb described in Zodiac’s June 26, 1970, letter was likely confined to the boundaries of the provided Phillips 66 map. Though it might initially seem improbable to determine a precise terrestrial location based on the materials, it becomes more plausible when considering the possibility that both the map and the code are meant to draw attention to observable elements—such as towns or landmarks—already printed on the map. The critical questions thus become:
1. What are we meant to observe?
2. How do we identify it?
3. And why are we being guided there?
In addition to the “4-inch” dimension, the placement of the crosshair over Mount Diablo by the Zodiac, merits close analysis. Historically, Mount Diablo has served as the site of two distinct survey markers. The first, established by Ransome of the Geological Survey, was part of a broader initiative to classify lands, geological formations, and mineral resources. This inland-focused survey mark is located approximately twelve miles from the point Zodiac appears to have utilized.
The second survey point—the one the Zodiac explicitly used—is located at the summit’s octagonal rotunda, which houses a large compass. Beneath this compass lies a foundational survey mark installed by General B. D. Cutts of the United States Coast Survey. This organization, established in 1807 by Thomas Jefferson (whose image notably appeared on Zodiac’s stamps used for the December 20, 1969, communication), was originally tasked with charting the coastlines and maritime boundaries of U.S. territories.
Prior to the rotunda's construction, a 75-foot Standard Oil tower and navigational beacon stood at the same site. Constructed in 1928, the tower was funded in part by the Department of Commerce to aid both maritime and aviation navigation. One of its primary users was the U.S. airmail system, which, like the concepts of flight and aircraft, recurs in Zodiac's communications—either explicitly or obliquely.
Given that the crosshair is anchored at a site historically used to survey the coastlines and that the Phillips 66 map shows land predominantly south of San Francisco, a logical hypothesis is that the target location lies within or just south of San Francisco and Contra Costa County. This assumption becomes crucial when evaluating the data that follows.
Multiple theories have been proposed to explain why the Zodiac used a crosshair marked with five X’s in his first bomb letter dated November 9, 1969. While these interpretations vary, a consistent theme involves overlaying the crosshair on Mount Diablo and adjusting it for magnetic declination. Given that the crosshair appears in a bomb-related letter, this orientation seems appropriate.
To explore this further, I overlaid Mike Cole’s magnetic declination grid, which is segmented into 30-degree intervals, onto the Phillips 66 map, centering it precisely at the point Zodiac indicated on Mount Diablo. Before applying the overlay, I removed any of Cole’s auxiliary lines that were unrelated to the essential numerals—3, 6, 9—or to the five X’s.
The resulting visual alignment reveals three significant locations—airfields—that align with crosshair points 6, 8, and 10 when rotated to mag north:
Buchanan Field Airport (37.5923 N, 122.0325 W)
Alameda Naval Air Station (37.7861 N, 122.3186 W)
Moffett Federal Airfield (37.2454 N, 122.0254 W)
These airfields, when contrasted with other crosshair vectors such as 0, 3, 9, 7, and 11—which point to areas outside the scope of the Phillips 66 map—become especially relevant. Their inclusion supports the idea that Zodiac’s intended references are constrained to locations visible on the map and possibly tied to aviation and navigation systems.
This realization brought me back to Alfred Loomis and the evolution of navigational technologies, specifically microwave radar and Doppler/omega/VOR systems. I was curious about how radians might factor into this, and I revisited the "4-inch" scale, speculating whether that might be a clue. This led me to study navigation principles like triangulation, which involves measuring radio signals between two stations to produce hyperbolic curves; where those curves intersect, a location—or “fix”—can be determined. However, triangulation requires complex equipment and calculation, which seems inconsistent with Zodiac’s claim that “the map coupled with the code will tell you where the bomb is set.” This statement implies a simpler, more intuitive solution.
That observation led me to trilateration, a related but more accessible method.
This concept gave rise to the idea that the Zodiac’s 4-inch crosshair should be converted to miles using the map’s scale (1 inch = 6.8 miles), resulting in a 25.6-mile diameter.
When this scale is applied to the three airfield locations, overlapping circles form.
Moffett Field, being further south, intersects only minimally and does not contribute to a useful trilateration fix. The other three circles (Buchanan Field, Alameda Naval Airstation, Mt. Diablo), however, intersect significantly.
In the black-and-white trilateration image, I marked the intersection area in red. On the Google map version above, I’ve outlined the same zone in black. Line 8 of the Zodiac’s crosshair with 5 Xs turned to mag north—pointing toward Alameda Naval Air Station—passes directly through this intersection. When looking at the original Phillips 66 map, the only significant feature labeled in this zone, is St. Mary’s College.
Though the Phillips 66 map labels it simply as “St. Mary’s College,” the institution’s full name is Christian Brothers St. Mary’s College. When punctuation is removed, the name consists of 31 characters—nearly identical to the 32-character cipher the Zodiac sent. Including either a period (after "St.") or an apostrophe (in "Mary’s") produces exactly 32 characters. British and Australian English often omit the period in abbreviations such as “St” thereby allowing the name to fit precisely within the cipher length. While this does not imply the Zodiac was of British or Australian origin, it may suggest familiarity with multiple linguistic standards—possibly through academic training in English.
Notably, this interpretation does not require a radian calculation, advanced cryptographic substitution, or any mathematical process beyond basic multiplication. Rather, it suggests the Zodiac’s code was a conceptual device, intended not to obscure—but to mislead. The true “solution” lies in observable features on the map, revealed through spatial reasoning and awareness of naming conventions.
In conclusion, this analysis supports the hypothesis that the Zodiac’s so-called cipher was not a literal code, but rather a narrative riddle—a performance of layered meaning meant to draw investigators toward a symbolic destination, using familiar tools: map, language, and perception. The precision with which he constructs this illusion further supports the idea that he possessed formal education—perhaps in English or a related discipline—and used that knowledge to manipulate public and investigative attention.