One of the figures may even reveal the biggest secret of all: the identity of the serial killer.
The most compelling evidence was four encrypted or scrambled messages, mostly sent to The San Francisco Chronicle Newspaper.
More than 50 years after the Z 340 cipher was carefully crafted and shipped, an international team of three code breakers, including an Australian mathematician, finally discovered the message.
Over the weekend, the FBI confirmed that the puzzle, which had puzzled cryptologists for decades, had been solved.
The focus is now on the killer’s remaining two figures.
Among law enforcement and the cryptology community, there is an intense fascination for the kind of case resolution information that can be stored within.
Dozens of podcasts, YouTube videos, blogs, and online forums are dedicated to crawling each cipher over and over again.
Claims are made and clues are shared. The discussion is lively.
This puzzle, the killer’s shortest cipher, was shipped on April 20, 1970.
It begins with the words “This is the zodiac speaking. By the way, have you cracked the last code I sent you? My name is ⎯⎯”.
The short handwritten note is followed by 13 symbols.
Some have theorized that the encryption is just a joke and that the killer would never reveal his identity.
One solution to the encryption claimed that the name in the code was ALFRED E. NEUMAN, the mascot of the legendary American comic. Angry magazine.
The first three letters of this particular cipher are A, E, and N. Some believe that these letters, symbolizing Alfred E. Neuman’s initials, reinforce the Angry theory.
The Z 32 cipher, also known as the map cipher, shipped on June 26, 1970.
Appearing at the end of a letter sent to Chronicle, the encryption is 32 characters long.
The encryption was part of a larger puzzle, which included a California road map.
At the time, the map was widely available at gas stations on the West Coast.
The Zodiac killer placed his trademark symbol, a circle with a cross, on top of Mount Diablo.
It appears on the mountain as a kind of compass, with the instruction that “0 is put in Mag. N.”
Magnetic North is slightly different from True North.
The natural question was, was Mount Diablo in any way meaningful to the killer or his victims?
At 408 characters, the Z 408 was the killer’s longest cipher.
It was solved by a North Salinas school teacher, Donald Harden, and his wife Bettye.
The Zodiac Killer divided this figure into three parts and sent it to two newspapers.
The killer demanded that the ciphers be printed or they would unleash a murderous rampage.
The newspapers published the puzzles.
While the Z 340 took 51 years to solve, Mr. and Mrs. Harden solved the encryption in a week.