On August 8, 1969, just six days after it was published, the Zodiac's code was solved by a California teacher and his wife. The code, among other things, stated that the Zodiac likes "killing people because it is so much fun."
Scan courtesy of the San Francisco Chronicle.
[Transcribed by me. Please note any errors you find in the comments.]
"A 'Murder Code' Broken"
A Salinas high school teacher who is an amateur cryptographer said yesterday he has broken the cipher sent to three Bay Area newspapers by someone claiming to have committed three Vallejo murders.
The unsigned letters to the editors of The Chronicle, the Vallejo Times-Herald and the Examiner said the writer had killed two Vallejo teenagers last December and a young woman on July 4.
Donald G. Harden, a history and economics teacher at North Salinas High School, saw the cipher, which was reprinted in newspapers, and told The Chronicle yesterday he and his wife had broken it after "about 20 hours of working on it off and on."
"As you can see," Harden said, "his spelling is rather poor and in some places he has made errors in the use of his own cipher."
These errors, Harden said, showed in incomprehensible groupings of letters, but the gist of the writer's message was fairly clear.
As Harden broke it, the cipher reads:
"I like killing people because it is so much fun it is more fun than killing wild game in the forrest because man is the most hongertue animal of all to kill something give eryetheyo a thrilling experience it is even better than getting your rocks off with a girl the best part of it I athae when I die I will be reborn in paradice and all the I have killed will become my slaves I will not give you my name because you will trs to sloi down or atop my collecting of slaves for my afterlife ebeo riet emeth hpiti."
Harden said the writer tried to make the cipher more difficult by using 12 different symbols for "e," the most commonly used letter in the language.
To further throw cryptoanalysts off the track, Harden said, the writer used a backward "q" 16 times, in an effort to make an analyst think that stood for "e," as, indeed, Harden first thought it did.
Harden said he broke the code by looking for four-letter patterns which would fit in with the word "kill."
"We felt that 'kill' would be used more than once," he said.
In the message, the writer used "kill" once, but "killing" twice and "thrilling" and "killed" once each.
Vallejo Police Sergeant John Lynch, in charge of the investigation of the murders and of the cipher letter writer, asked The Chronicle to send Harden's code to him for further checking, which was done.
When the ciphers first came to police attention, Navy cryptographers were asked to attempt to break the code, but with no reported success.