Decoding the Exorcist Letter: Zodiac’s Symbols as a Hidden Map of the Bay Area
Sometime between
April and October of 2010, I was using Google Maps / MapQuest to trace the
routes the Zodiac would have taken from one crime scene to the next. As I
panned the map toward the Paul Stine crime scene, two shapes on the screen
caught my attention. They looked strangely familiar - almost identical to the
symbols in the Exorcist Letter.
To align the symbols with what I thought I recognized on the map you have to rotate the symbols 90 degrees clockwise:
The shapes that
stood out to me were what we now recognize as Treasure Island and Alcatraz
Island. The long horizontal line beneath them corresponds to a section of I‑80
- the Dwight D. Eisenhower Highway - that crosses over Yerba Buena Island.
Panning up on the
map I was then able to see another symbol the Zodiac drew – the dot with a line
protruding from it.
This newest symbol above
represents Brooks Island. So here we see Brooks Island, Treasure Island, a
portion of I-80 known as the Dwight D Eisenhower Hwy, and Alcatraz Island.
In the image above,
I’ve added the dot from the Exorcist Letter symbols. Its position appears to
point to something located above Paradise Beach and below the town of
Strawberry. The closest geographic match in that area is Muir Woods
National Monument.
The remaining
Exorcist Letter symbols take a bit more work to explain. A couple of different
locations could fit their shapes, so I’ve broken the analysis into smaller,
more manageable sections.
The image above shows Treasure Island, Alcatraz Island, the section of I‑80
known as the Dwight D. Eisenhower Highway, and the next symbol I want to
examine. This particular symbol appears to branch off from I‑80. In theory, it
could represent any street from the Embarcadero all the way to about 10th
Street in San Francisco — roughly where I‑80 transitions toward US‑101.
However, because of the symbol that follows, I believe the most likely candidates fall between the Embarcadero and 5th Street. Fifth Street is significant because it sits near the point where I‑280 begins (slightly east of I‑80), and that becomes important when interpreting the next
set of symbols.
Based on the overall structure, I believe this line represents one of two possibilities:
1. The stretch of the Embarcadero from the Ferry Building to I‑80
2. Mission Street, from 5th Street up to I‑80
The reasoning behind these two options will become clear shortly.
The T symbol I believe represents 7th St and Mission St as shown below:
You can see that 7th Street ends at 16th Street, which provides access to I‑280 at that point. In the Exorcist Letter symbol, the next line is drawn more boldly - similar to how I‑80 was represented earlier - and it angles downward in the same direction that I‑280 runs on the map. Taken together, the symbols I’ve shown represent 7th Street, Mission Street, and a portion of I‑280.
The final symbol in the Exorcist Letter sequence is the following:
If you follow along on a map from 7th Street via I-280, you reach the following:
I spent a considerable amount of time researching each of the locations represented in the Exorcist Letter symbols. At one point, I even wrote a piece arguing that all of them connected back to the Department of the Interior. I would still like that to be true because it would tie neatly into several themes within the Zodiac case. But the strongest conclusion I can make at this point is that the common thread among these locations is conservation. Each site carries its own history of preservation, protection, or environmental significance - even if for different reasons.
The symbols, when rotated 90 degrees clockwise, correspond to the following locations:
1. Muir Woods - a national monument protected since January 9, 1908, under the Antiquities Act of 1906, administered by the Department of the Interior.
2. Brooks Island - incorporated into the East Bay Regional Park District in 1968. Although not directly managed by the Department of the Interior, its conservation policies are shaped by federal standards that influence regional parks nationwide.
3. Treasure Island - designated a California Historical Landmark, with preservation efforts that likewise fall under broader Department of the Interior conservation policies.
4. Alcatraz Island - governed by the National Park Service since shortly after the prison closed in the 1960s and listed on the National Register of Historic Places since 1976. The National Park Service operates under the Department of the Interior.
5. The Embarcadero - home to both the Ferry Building and the Audiffred Building, each recognized as historic landmarks with their own preservation histories. If one symbol corresponds to this area, the Audiffred Building is the stronger candidate, given its long association with maritime clubs and the Navy references found elsewhere in the Zodiac case. It became a San Francisco Landmark in 1968 and was added to the National Register of Historic Places in 1979. Another possible match for this symbol is the intersection of 5th and Mission, where the U.S. Mint - a National Historic Landmark since 1961 - is located. Though I struggle to see a direct Zodiac connection here, one could stretch the association to the phrase “the price of my head.” Note: I originally wrote this article in 2014. In 2025, I was able to find a connection to the U.S. Mint, but it is not something I am prepared to talk about now.
6. 7th and Mission - the site of the James R. Browning U.S. Federal Courthouse and Post Office, listed as a National Historic Landmark since October 14, 1971. The name “Browning” stands out to me personally, and this building houses the Ninth Circuit Court of Appeals.
7. Industrial Street and Oakdale Avenue - this final symbol puzzled me for a long time. There is no park, landmark, or historic designation at this location. However, beneath the surface lies the Islais Creek Estuary, part of the Bureau of Reclamation - which is under the Department of the Interior.
What do all these locations have in common?
As much as I would like to tie every one of them directly to the Department of the Interior, the strongest unifying theme I can identify is conservation.
Each site carries its own history of preservation, protection, or environmental stewardship - even if the reasons and governing bodies differ.