These four papers document the cryptanalytic and forensic investigation that identifies Marvin Merrill as the individual encoded in the Zodiac Killer's Z13 cipher. The solution was first made possible by Alex Baber's discovery of the 2×7 columnar permutation construction. The papers are intended to be read in order, though each stands alone.
Paper I
Structural Resolution of the Zodiac Killer's Z13 Cipher
The primary cryptanalytic paper. Establishes the 2×7 box construction,
presents both the known-plaintext and ciphertext-only attacks, recovers
the keywords Elizabeth and Cherijo, and provides an information-theoretic
analysis of the solution.
Paper II
Keyword Corroboration for the Z13 Cipher
The companion Bayesian analysis of the two keywords that independently
generate the Z13 permutation and substitution keys: Elizabeth and Cherijo
with very small joint null probability.
Paper III
Solving the 18-Character Z408 Tail: An Isologue of the Z13 Cipher
Argues that the Z408 tail (EBEORIETEMETHHPITI) is doubly encrypted.
Part 1 shows the 13-character residue is an isologue of Z13 under a
fwd/fwd box construction. Part 2 documents the Robert Emmet red herring
and its connection to Marvin Margolis's naval commanding officer.
Paper IV
Bayesian Identification of the Zodiac Killer: Three Independent Entry Points
A Bayesian framework combining three independent entry points:
the 1947 Black Dahlia connection, the Z13 cryptanalytic result,
and forensic evidence obtained from the Merrill family in 2024.
Presents the positive and negative indicators and the asymmetric
burden of refutation.