The solution to one of the Zodiac Killer’s cipher, unsolved for 51 years, was cracked by a team of citizen codebreakers earlier this month, with the FBI confirming the decoded message’s authenticity.

The “Z-340” message — coined that as it contained 340 characters, a mix of letters and symbols — was first sent to the San Francisco Chronicle in November 1969, amid of string of ciphers, threatening letters and evidence (swatches of a victim’s shirt) that the Zodiac Killer sent to the newspaper.

While some of the Zodiac Killer’s ciphers were decoded at the time, the “Z-340” message remained unsolved for 51 years, until the codebreakers — David Oranchak of the U.S., Sam Blake of Australia and Jarl Van Eycke of Belgium — revisited the cipher using Blake’s decryption software; in a YouTube video posted Friday, Oranchak detailed how the message was decoded and why it took so long. (In addition to the Zodiac Killer’s not-great spelling, he also erroneously misplaced characters in his own code.)


Ultimately, the codebreakers translated the cipher as:

“I hope you are having lots of fun in trying to catch me that wasnt me on the TV show which brings up a point about me I am not afraid of the gas chamber because it will send me to paradice all the sooner because I now have enough slaves to work for me where everyone else has nothing when they reach paradice so they are afraid of death I am not afraid because I know that my new life is life will be an easy one in paradice death.”

(The line about the TV show refers to an October 1969 incident where someone posing as the Zodiac Killer called into a San Francisco morning show to speak to lawyer Marvin Belli.)

Oranchak submitted the trio’s findings to the FBI earlier this month, with the agency acknowledging the code had been cracked Friday:

Speaking to the New York Times Friday, Oranchak said, “The message in that cipher. I don’t see it as being helpful to them. It’s more of the same junk that the killer liked to write about. It’s just intended to hurt people and make them afraid.”

Blake added, “It’s considered one of the holy grails of cryptography. At the time, the cipher had resisted attacks for 50 years, so any attempts to find a solution was truly a moonshot… Not only were we lucky enough to find the needle in the haystack, but we were lucky enough to pick the right haystack in order to start searching for the needle.”

The Zodiac Killer is confirmed to have killed at least five people in the Bay Area in the late Sixties and early Seventies. His identity remains unknown, and an April 1970 cipher containing 13 characters — “My name is _______” precedes the message — is still unsolved.