51 years ago the notorious Zodiac killer sent a coded message to the San Francisco Chronicler. It has now finally been solved by an Australian mathematician.
This post was originally published on December 12 at 1:05pm.
The Zodiac Killer’s code, also known as the ‘340 cipher’ was sent into the newspaper on November 8, 1969. It was made up of 63 characters that were made up of letters and symbols.
The 340 cipher has haunted the police, Federal Bureau of Investigation (FBI) and cryptologists for over five decades. But now it has solved.
Zodiac Killer code solved
Dr Samuel Blake, along computer programmers David Oranchak and Jarl Van Eycke, finally cracked the Zodiac Killer’s code earlier this month.
The team utilised codebreaking software developed by Van Eycke to solve the mystery. Over 650,000 simulations were runs before it was solved on December 3, 2020.
The message revealed the following:
Dr Blake and the team sent their findings to the FBI, which has confirmed its legitimacy.
“The FBI is aware that a cipher attributed to the Zodiac Killer was recently solved by private citizens,” the FBI said on Twitter.
“The Zodiac Killer case remains an ongoing investigation for the FBI San Francisco division and our local law enforcement partners.”
— FBI SanFrancisco (@FBISanFrancisco) December 11, 2020
The note is said to be consistent with other letters sent by the killer during his killing spree.
The final letter was sent in 1974and included praise for the movie The Exorcist.
How it was solved
It seems that the Zodiac Killer made a mistake with the cipher, which would explain why it has taken so long to solve.
Reagrdless, one phrase in particular helped Dr Blake and the team solve the cipher.
“During the year we tested, by trial and error, around 650,000 different reading directions through the cipher. This search turned up — more or less — nothing,” Blake said on social media.
“However, one of these searches uncovered a surprising combination of words: GAS CHAMBER. That such a macabre phase should pop up in a sea of noise warranted further attention.
“From this fragment, David, Jarl van Eycke and I reworked the key and corrected an error Zodiac made in his diagonal enumeration of the second vertical segment of the cipher.
“Jarl’s fantastic program, azdecrypt, was essential in this process.”
Despite the time span of his murders and the numerous taunting letters sent, the Zodiac Killer has never been identified. While the Zodiac has claimed to have committed 37 murders, only 7 victims have ever been confirmed by the policed.
The case is still open in four jurisdictions in California.