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MYS406: A theory claims the Zodiac wasn’t a single murderer at all—just real crimes stitched together by fake calls and letters. So Jimmy Akin and Dom Bettinelli put that claim on trial.

They lay out seven crucial pieces the hoax theory has to explain: two phone calls, the early letters (including the Z408 cipher), the Lake Berryessa costume symbol, the message on Brian Hartnell’s car door, and the later letter containing a bloodied piece of Paul Stine’s shirt. Then they weigh each item: is a hoax explanation actually more plausible than “one killer building a persona”?

If the Zodiac was invented, who made that first call—and how would they know what they claimed to know? If the letters were fabricated, why do they contain details the public didn’t have—and why would supposed insiders risk evidence-tampering crimes? If Lake Berryessa was an impersonation, why would someone commit a rare “identity” copycat attack so quickly, in the same region, after only a couple letters?

The conversation also digs into the practical problem hoax theories often face: probability stacking. Even if one element could be faked, a full hoax requires either multiple independent people repeatedly making the same bold decision… or an expanding conspiracy where every added participant increases the chance of mistakes, exposure, or whistleblowing.

Jimmy also critiques how the hoax proposal is argued—weak handwriting comparisons, speculative access-to-files claims, unclear motives, and shifting suspects—then offers a clear bottom line: the single-killer hypothesis fits the evidence with fewer unlikely assumptions. And at minimum, a man in an executioner-style hood with the Zodiac symbol attacked at Lake Berryessa—meaning there truly was a “Zodiac” killer in the most literal sense.

The episode closes with listener feedback on the Calvine UFO sighting, including fan art, alternate interpretations, and a thoughtful exchange about when (and how cautiously) AI tools should be used in research.

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Links for this episode:

• Horan’s book The Myth of the Zodiac Killer
• ZodiacKillerFacts.com
• Critique of Horan’s proposal
• Critique of Robert Graysmith’s book Zodiac

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Chapters

• 0:11 – Previously…
• 1:23 – Intro
• 2:57 – Reason Perspective
• 4:36 – 7 things to explain
• 5:18 – 1. The first phone call
• 12:22 – 2. The first letter
• 32:51 – 3. The second letter
• 33:27 – 4. Zodiac symbol at Lake Berryessa
• 37:30 – 5. Message on car door
• 49:05 – 6. The second phone call
• 55:05 – 7. The third letter
• 57:20 – Thank you to Patrons
• 57:51 – Sponsor: Rosary Army and School of Mary
• 58:15 – Sponsor: The Grady Group
• 58:31 – The scope of the hoax theory
• 1:05:04 – Others accused
• 1:10:36 – A changing theory
• 1:16:33 – Jimmy’s own theory
• 1:19:37 – Bottom Line
• 1:23:13 – Further Resources
• 1:23:33 – Feedback on #395 Calvine UFO Sighting
• 1:39:09 – Your mysterious feedback
• 1:39:50 – Thank you to Oasis Studio 7
• 1:39:54 – Jimmy’s YouTube channel
• 1:40:37 – Next Time: Library of Alexandria and more Patron questions
• 1:41:11 – Follow the show
• 1:41:23 – Get your Mysterious merch
• 1:41:30 – Show notes
• 1:41:37 – Become a Patron
• 1:41:46 – Become a Sponsor
• 1:42:45 – Outro

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